Other mistake: When Hilts and Ives are taken down to the cooler for the very first time, just after arriving at the camp, watch the wall as the door is closed by the guard behind Ives - it very obviously moves as the door slams shut.
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.
Other mistake: When the three Americans invite the British to join their 4th of July celebration, Hilts plays the flute with his right hand the wrong way round on the instrument.
Other mistake: When Steve McQueen first comes to the camp he voluntarily gives up a pair of wire cutters. No POW would have done that. Tools of that nature were too hard to come by.
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.