Factual error: A convoy of open trucks arrive at the camp bringing the latest batch of prisoners, many of whom are carrying rucksacks and tote bags of clothing and other possessions. Where did they come from? Combat servicemen in World War Two did not carry overnight bags with them - a change of clothes or a handy supply of toiletries was the least of their concerns. A prisoner of war arrived in the camp with the clothes he stood up in and nothing else.
Factual error: Many of the prisoners are wearing watches, which is incorrect. Upon arrest a prisoner's watch was confiscated. This prevented them using them to bribe or barter with corrupt guards (and as this film acknowledges, there were plenty of those) as well as making coordination of meetings or escape plans difficult.
Factual error: Why is Hilts not wearing a uniform? A serving officer captured behind enemy lines in civilian clothing risked being shot as a spy. If a prisoner's uniform was too worn or damaged to wear, it was routine for the German authorities to replace it - a P.O.W. in civilian clothes is an obvious escape risk. He is wearing a pair of tan chinos and a cut off sloppy Joe sweatshirt, both ridiculously anachronistic - Sixties hipster fashions - and nowhere even close to a World War 2 uniform.
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.
Factual error: The entrance to tunnel Dick is shown improperly; the trap door was on the side of the drain basin, not the bottom. This was discussed in the Brickhill book, and subsequently verified by research on the site (shown on the US television program NOVA) which found the original door and its lifting handles.