Continuity mistake: When John Mills is looking through the periscope whilst searching for the German battleship the side view shows him moving the periscope from right to left, but when it suddenly cuts to a shot of what he is actually seeing through it the periscope is strangely moving from left to right.
Continuity mistake: During the opening of "This Is the Army" [the stage musical], there is a large choir of men singing the opening number, "Some Dough For The Army Relief": from about the second row back, the men's mouths are moving appropriately for the lyrics they're singing, but much of the front row is singing with these obnoxious cheesy grins, not even bothering with more than the most feeble attempt at proper mouth movement. [This is painfully evident during the line "let him do what we had to do."]. (00:48:50)
Continuity mistake: In the scene where the tank crew meet up with the weary band of soldiers, Fred Clarkson (Lloyd Bridges) has a very distinctive graze on the right side of his forehead. It seems to disappear then appear then disappear during the film. When Clarkson lies injured there is no sign of the graze - there should at least be a small mark of the graze but there is nothing.
Continuity mistake: In this scene we see the two German pilots are flying low over a flock of flamingoes who get startled and fly towards the plane. We get a inside cockpit view of the pilots and the starboard side window has not a mark on it and is clear. In the next shot the pilot shouts out the words "Look out" Look Out" and the window is peppered with bird feathers. Then a moment later the glass is clear again and this time we see and hear the feathers hit the window.
Revealing mistake: When the mice are feeding the cat, the cat sits up and a mouse passes through his head.
Continuity mistake: When Jerry launches his egg carton, there are initially three light bulbs in the back, but when he releases the bulbs, there are now four.