Continuity mistake: When Cadet Major Morelan is unbuttoning his jacket he unbuttons the top 2 buttons and the bottom 2 buttons. This leaves the middle 3 buttons fastened. He then sits down and is talking to Tom Cruise, Sean Penn and 1 other Cadet. In the next shot when he stands up, the bottom 3 buttons are now unbuttoned and only 2 buttons are fastened. He had sat down with his hands on his knees and that never changed. The button could not/would not unbuttoned itself.
Audio problem: When Bunny (Ramon) is, as Zorro, spelling out "Zorro" on the wall with his whip, the number of whiplash sounds does not match the number of marks in the wall.
Visible crew/equipment: When Dr. Boyle arrives in Boston, you can see the reflection of some crew members on the car.
Continuity mistake: About half way through the movie, the three main characters are in a loft. When the Asian girl grabs the postal worker's jacket, a cassette tape falls out of his pocket. As the girl bends down to pick up the tape, the camera shows here reaching with one hand, and then the camera switches to a close-up of her picking up the tape with the opposite hand.
Continuity mistake: While Chevy's car is being covered with radioactive foam from the truck in front of him, following shots alternately show the car with and without foam.
Continuity mistake: At the end of the film the plane they are initially flying on is a typical passenger plane, but when the Muppets are thrown out, the plane is one used for skydiving.
Factual error: There could never be an aircraft of World War 2 vintage with the call sign "Yankee Zephyr". If it was a US aircraft (it appears to be) it would have the call sign "Yankee Zulu". If it was an RAF aircraft it would be "Yoke Zephyr". This all changed when the phonetic alphabets were standardised by NATO in the Fifties, but the DC3 in this film is supposed to have crashed before the end of World War 2 in 1945.
Continuity mistake: When Snoopy is at the library, he picks out a book and you can see there is nothing on the front cover, but when we see a close up of the book in the next shot, the words "How to Perform Magic" have appeared.
Other mistake: There's no way Harry could've smashed the cigarette vending machine at the gas station without somebody inside seeing him.
Continuity mistake: Jack sees the car drive into the creek and runs to check for anyone injured. Jack dives into the water and you see the car submerge completely. Jack is then looking around and the car's trunk is sticking out of the water, then submerges yet again.
Deliberate mistake: When "Henry Faber" discovers the phony airfield, several helicopters with Army markings are among the aircraft visible. Although the Army did use helicopters experimentally during WWII, those used bore no resemblance to those shown in the film.
Other mistake: Towards the end when Janet, Brad, Oliver and Betty are singing "We're going to do it anyhow," as they are dancing down the aisle, Betty very visibly trips and grabs Oliver to stop from falling over.
Continuity mistake: In the raft scene the boy at the front right, from his view, is kneeling on his left leg. When the camera cuts behind them he's suddenly kneeling on his right leg and remains on this leg through every other angle.
Continuity mistake: Set in the 1930s, Steve Martin is teaching a class of grade-schoolers in one scene. This would only be picked up by Canadians, but one of the many flags on the wall is the new (as of 1965) Canadian Flag - Red Maple Leaf with two red panels on either edge.
Revealing mistake: When Joe has died of blood poisoning there is a close up of his head and neck, you can see him breathing and his eyes flicker.
Factual error: Franklyn Hart keeps his car running by pumping out the gas from the bottom of abandoned gas pumps which the pumps themselves couldn't reach. In reality, as this gas is on the bottom, it would be full of sludge and garbage, and since it has been sitting there for 20 years, it would barely be usable and would probably damage the engine. He certainly wouldn't be able to do high speeds with it.
Visible crew/equipment: During the opening sequence Cole does a backflip to get down from a tree and lands behind some tall grass, as he pushes the grass aside and steps through you can see the stuntman who did the backflip trying to hide behind him.
Continuity mistake: When Chuck Norris is battling with the Triads at Mako's house, a oriental box is knocked off a table in the first shot when a Triad is slammed against the table it is on. In the next shot of the table, the box is back in its' position.
Factual error: After the autopsy of "Sheila," the medical examiner tells the entomology expert that "she has no internal organs whatsoever." Yet, we're looking at "Sheila," and she has not been cut open at all, certainly not in the standard Y-shaped incision used in autopsies. Wouldn't even the worst medical examiner at least look inside before stating that internal parts were missing?
Continuity mistake: When Stallone and Williams are on the back of the train, Stallone smashes the window. Cut to Hauer. After this, the window is shown again, and the hole in it is larger than it was when broken.