According to Ivan Reitman, Bill Murray insisted that Harold Ramis be cast as his friend for two reasons: 1. They were long-time friends in real life. 2. So Ramis could help Murray re-write his dialogue or help him improvise.

The cast improvised virtually all of the dialogue where they sit around and tell their back stories. This includes Bill Murray's lines about "Lee Harvey" 'making it' with a cow, and calling Sgt. Hulka a "big toe."

According to Ivan Reitman in the DVD commentary, the scene where Bill Murray is loading the rich woman's suitcases into the trunk and he hits himself in the crotch was an accident. Murray really did hit himself in the crotch with the case, thus his very real line "Oh, my balls."

According to Ivan Reitman in the DVD commentary, during the scene where the recruits receive their basic training haircuts he did not tell the actors that real Army barbers would be shaving their heads until the scene was shot. He lined all of the actors up and shot the scene as scripted to get their genuine reactions to their heads being shaved. John Candy became depressed after the scene was shot. This is why you see him picking up his hair and looking sad when he walks out of the barber shop. Since Bill Murray and Harold Ramis were bigger names at that point than the rest of the cast, they were required to cut their hair shorter, but not to shave their entire heads.

The US Army was actually very helpful and cooperative during filming, which surprised Ivan Reitman since the script depicts the military as being made up largely of buffoons.

Continuity

When Winger is going AWOL, his backpack keeps appearing and disappearing during the scene when he is lying on the ground.

When Winger's girlfriend leaves him, she puts her left boot on twice.

When Ziskey attacks Winger, before they are picked up by the MPs Winger's duffel bag moves from left of his head, to being right under his head.

When Ox gets his hair cut at the beginning of basic training, he is shaved nearly bald. When he talks about why he joined the Army, presumably at the end of the same day, his hair looks as if it has grown out for at least two weeks.

In the bus station scene Sean Young's character is an E5 with a stripe on her rank insignia, when she is at the graduation scene she is an E4, no stripe.



Factual errors

While Ox and several other characters got true boot camp haircuts, taken down to the barest of stubble, Winger, Zisky, Elmo and Psycho among others have haircuts that are too long to be the norm at the start of boot camp.

Neither John nor Russell has their hair cut short enough for Army recruits.

Even at the time this movie was made, there were weight restrictions on joining the army. The maximum body fat percentage allowed was 28% before joining boot camp, and anything over 33% the military considers "obese". Thus, there is no way that Ox would have been allowed to enlist, mostly for his own safety and health, as overweight/obese recruits would end up being processed out early for not being able to take the rigors of basic training.

Company commanders, or drill Sergeants, do not follow their recruit graduates to their next assignments, which is usually a specialist training school, or in this case to Italy to prove the EM-50's capabilities. Sgt. Hulka in reality, after the mortar accident, would have forced him to retire, or to remain at recruit training command to finish out his tenure. Furthermore, he would never show up at a new command still healing while he was still attached to the recruit training command (RTC), and also because Sgt. Hulka had nothing to do with the special drill show Winger had supervised. Hulka's transfer order alone would have taken at least sixty to ninety days to complete.

During basic training civilian clothes are locked up in a storage room therefore none of the troops would have access to them.



Incorrectly regarded as goofs

When John is taking the woman to the airport, he ends up heading north across the 2nd Street bridge into Indiana from Louisville. The airport is actually south of downtown Louisville. However, although many of the vehicles in the city scenes have markings or signs indicating the filming was done in the Louisville area, nothing in the dialogue specifies that the setting is Louisville or any other specific city.



Revealing mistakes

There is a scene where Cpt. Stillman (John Larroquette) pulls the pin out of a live grenade out of frustration that there was "no action". However, if you look closely at the grenade, it is painted blue. In the military, blue is the code color for "Inert" or disabled. This is to make sure that live explosives or weapons are not used in training sessions for obvious reasons.

During the escape, Ox knocks over a rusty barrel, and reveals a shiny, spotless interior.

When the door is exploded, the explosion and smoke happens, but the unexploded "plastic explosive" is still visible afterwards.

The Sergeant states that basic training will start at 0500 (5am). In the next shot we see the dawn breaking. Since the movie takes place in fall/winter, there would be no sunrise until after 7am.

When the men assemble on the parade ground for their impromptu performance at graduation, a yellow hash mark is visible on the ground that tells them where to turn right as they double-time into position.



Miscellaneous

The water tower seen in the Fort Knox settings can also be seen when the setting changes to the Czech fort.

Winger just got "a hundred dollar shine on a three dollar pair of boots." Yet we get a shot later of him walking you can clearly see his boots are not freshly shined.



Anachronisms

The manual for the EM-50 that Harold Ramis' character is reading in the hangar states the manual is from the War Department instead of saying Department of Defense. The Department of War existed from 1789 - 1947.

Soviet officer is wearing a uniform from the late-1940s.

In 2005, the MPAA approved the film's extended cut with the certificate #41708. Despite this, the film's original certificate #26302 is strangely shown at the end of the extended cut.

On all releases starting with the 2005 Extended Cut DVD, the 1998 common fanfare from the 1993 Columbia Pictures logo is strangely heard.



Audio/visual unsynchronized

When Winger's platoon arrives at the graduation, the music has stopped, yet the band conductor's baton continues to move for several seconds.

In the end scene at the airfield, Bill Murray and Harold Ramis' characters (and others) are welcomed as heroes. Ramis's character is speaking to reporters but what he's saying doesn't match up to his lips talking.



Crew or equipment visible

When Winger and Russell are on guard duty for the EM-50, the camera crew are reflected in the EM-50's paint between their heads.

The crew's moving feet are reflected in the side of the Urban Assault Vehicle while John and Russell discuss stealing it.

During the rescue toward the end of the movie, when a rocket is fired from the Urban Assault Vehicle toward a guard tower, a crew member is clearly visible crouching at the left of the scene attempting to conceal himself behind part of a building.

In the training shots, where all the soldiers are covered in mud and running through the field with the music playing, in the wide-screen version, the camera crew is visible on the right for a few seconds.

After the platoon arrives in Italy, stage lights can be seen in the barrack window's reflection.



Errors in geography

Traveling north from Italy to Germany, as Winger and Ziskey went with the RV to see their girlfriends, and their squad traveled in pursuit, one would have to take a RIGHT into the Czech Republic, and a LEFT into Germany, not a left into the Czech Republic and a right into Germany as the road signs falsely indicated.

Colonel Glass says he will transfer Capt. Stillman to a weather station above the Arctic Circle if he screws up again. In the end scene, we see it did indeed happen to him. The newspaper says "Nome News." Nome, Alaska is well below the Arctic Circle and has much milder winters than the interior of the state. Also, there is no Army or military presence in the city. All the Army installations are in Anchorage and Fairbanks.

(at around 18 mins) The 1975 BMW 530i is a US version. You can tell by the big 5 mph crash bumpers and fake plate just resting on the real plate to hide it. It would not be in Germany, a German model would.

In Louisville, Ky., the airport is not across the river.

In the "rude cab fare" scene, a significant portion shows the river located on the driver?s side, but then he turns right to cross the bridge, making them travelling in the opposite direction.



Plot holes

When John is commiserating with Russell over losing his job, his car, his apartment and his girlfriend, there is no visible or spoken evidence explaining how or why he lost the apartment.



Boom mic visible

In the barracks, the first time Sgt. Hulka meets with his troops.



Character error

When Sgt. Hulka calls on the radio from Czechoslovakia, he sends the co-ordinates as "416 397". Without specifying a grid zone designator and a 100 km square identifier, nobody would have any idea which area his location would be in. A simple six figured grid reference could be in any 100 km square area. Russell would not have been able to recognize it as in Czechoslovakia.

Sergeant Hulka states at one point that he has been in the Army for 28 years, yet on his dress uniform he wears the ribbon for the WWII Victory Medal. Since the film is set in the early 1980s, Hulka's date of enlistment would have to be in the early 1950s, making him ineligible for that award. Captain Stillman wears the United Nations Service Medal for Korea, but he is far too young to have fought in the Korean War.

When Sgt. Hulka first meets Capt. Stillman, at first Hulka fails to salute the officer. Then after the glare given by Stillman, Hulka raises and lowers his salute without waiting for Stillman's salute. The correct custom and courtesy on saluting is that the enlisted or lower officer rank raises their salute and holds it until the higher rank acknowledges it, usually by returning it but can be done by a simple nod of the head. Then the junior rank may lower theirs. However, given Sgt. Hulka's length of military experience as well as his general demeanor, it is likely that his failure to salute properly was intentional and intended to be a sign of disrespect.

Sergeant Hulka tells the recruits during in-processing that they are to refer to him as "Sergeant". In basic training, drill sergeants are always referred to by recruits as "Drill Sergeant" and never just "Sergeant".

Prior to the first run, Sergeant Hulka tells the men that the run will be 10 miles rain or shine. The next morning Hulka tells the men the run will be 5 miles.