Revealing mistake: Towards the end of the film, when Hilts (Steve McQueen) is in a motorcycle chase with the German guards, if you watch closely, when the camera cuts away from Hilts and to the German motorcyclists, you might be able to notice that one of the guards chasing McQueen IS actually McQueen! They used him to play one (or maybe more) of the guards because of the experience he had with motorcycles. This can also be seen in some behind the scenes footage on the DVD version of the film.
Factual error: When McQueen steals the motorbike from the German soldiers and rides off it is clearly a Triumph, a British make, not a BMW or Zundapp which was what the German army used. More to the point it looks like a 1960s model.
Continuity mistake: When Roger is in the van talking to Macdonald, his face is deliberately dirty and stubbled - but when they are about to shoot him, he is clean-shaven. similarly with his bruises which seem to magically disappear by the evening of the first day.
Continuity mistake: Check out the memorable scene when Hendley and Blythe, trying to reach Switzerland in a stolen training aircraft, fly over marvellous Castle Neuschwanstein. According to Hendley, they've almost made it, just 20 minutes of flight and one mountain range left to cross. This is quite funny because the Neuschwanstein shot reveals that they're actually flying straight in the wrong direction. The camera faces south, the plane moves from right to left, meaning they're heading east, straight away from the Swiss border which is just 50 kilometers west of the famous castle.
Visible crew/equipment: In the scene where everyone is lining up to receive the moonshine that the Americans made you can see a crew member on the left hand side. He is wearing a red baseball cap and modern clothes. He is motioning for the extras to go into the main shot to get the alcohol. (Widescreen edition).
Continuity mistake: When Hendley and Blythe emergency-land their plane, it dashes into a copse. Both wings are cut off by trees and stay behind, while the fuselage runs on for several meters, finally coming to a halt with the tail facing down and the cockpit up. Next shot (pilots exiting the plane), the crash site looks very different: The tail now points into the air, cockpit down. And even worse, the wings have returned to the plane, I mean they are still cut off, but now positioned neatly on both sides of the fuselage instead of all those meters behind where you'd expect them.
Continuity mistake: In the scene where Steve McQueen is pulling wire across the road, and attaching the end to the pole to trip up the motorcycle rider you can clearly see two shadows on the ground of Steve in opposite directions due to the camera lights.
Continuity mistake: When Blythe starts to lose his eye sight, he tests his eyes by closely examining the forged document. But the document he holds up is different from the document we see in the later shots.
Continuity mistake: When Hilts and Ives are put back in the cooler after their first escape attempt, the dirt on their faces in the corridor outside their cells doesn't show up in the same places when they are actually in their cells.
Continuity mistake: Just after Ashley-Pitt has worked out how to hide the dirt, we see Ramsay raking the dirt and Bartlett and MacDonald walk out from behind a building and look at him, but in the next shot, Bartlett and MacDonald are looking at each other.
Plot hole: Roger's initial briefing at the beginning of the film states that 'Tom' goes out from 104 and 'Harry' from 105. Despite this the goons are said to be in 105 when they find the entrance to Tom.
Revealing mistake: When James Coburn and Charles Bronson are pretending to be Russian prisoners and attempting to walk out of the camp, if you look in the open windows of the huts in the background (past the men leaning out the windows), in several of the huts you can see that there is nothing inside, with wooden beams/braces visible to hold up the walls.
Factual error: As Steve McQueen is making his 'great escape', he drives his motorcycle through a gap which a chasing motorcycle and sidecar can't squeeze through, so it crashes. Cut to a crane shot of the retreating McQueen racing into the distance. Keep your eye on the left of frame and into view, on top of a building, is a distinctly un-1940s TV aerial. It's there for a full 7 seconds.
Continuity mistake: The position of the propeller crank changes between when Hendley first hands it to Colin and when Colin begins to crank it.
Continuity mistake: In the scene where Ives attempts to climb over the barbed wire fence, a long shot shows Ives in foreground and a line of men, including Hilts, in the background. In this shot, Hilts notices Ives and begins to run towards him. In the next shot, a close up of the line, we see Hilts still standing motionless, before noticing Ives and beginning to run towards him. Again.
Other mistake: Ramsay sports on his tunic the ribbons for the Distinguished Service Order, the Military Cross, either the 1914 or 1914/15 Star, the British War Medal and the Victory Medal. Unfortunately, the ribbon bar for the last three has been sewn onto his tunic upside-down - it reads, left to right as seen, VM, BWM, Star, when it should read Star, BWM, VM.
Continuity mistake: While describing the escape process, Roger says that "Tom will run north from the 105." He is interrupted, then says, "as I said, Tom will run north from 104."
Audio problem: The sounds of the prisoners laughing and bantering about during the 4th of July moonshine scene is obviously a looped soundtrack as the same exact sounds and volume are heard at least four times during this scene.
Character mistake: When Werner goes to see Hedley for helping finding his "lost" papers, Hedley is playing chess. The chess set is set up incorrectly. When the men are set up properly, each player has a light colored square in the right-hand corner. In the movie, the game is set up so that the light-colored square is in each player's left-hand corner. This "beginner" mistake puts the king and queen in the wrong positions.
Character mistake: When Sedgwick is bringing the cement tunnel lid to Willy, somebody yells out "Hey Hendley" and Sedgwick answers "Hello boys". He was called by the wrong name.
Answer: It's German, although I can't quite make it all out. The Germans tell him to stop (sounds like one says "hey you" in English). He asks what this is all about and, in English, the soldier accuses him of being English. Bartlett acts offended at the idea, and at being threatened with a pistol. The soldier then asks if he's German, he says something in the affirmative, and the soldiers apologize as they climb back in the car.
It sounds like the last line from the German Officer is" Free to Go" in English.