The bombers shown flying over the stalag in the stock footage were B-17 Flying Fortresses. However, the wreckage shown of the crashed bomber was from a B-25 Mitchell bomber.
Klink and Hogan are in Klink's office. Klink is wearing his uniform but not his cap. When a flight of planes goes over both Klink and Hogan dash out of the office. When Klink comes out the front door he is wearing his overcoat, cap and gloves and is carrying his swagger stick.
There are 2 pictures hanging on the wall next to the door in Klink's office. The usual one with Hitler speaking into a microphone, where the listening devices is located. And another one between that one and the door. This second picture is only seen in a couple of episodes.
There is an opening of a tunnel seen in the background past the main gate. This was the tunnel that was used in previous episodes that was bombed.
When Kinchloe sticks his head up through the roof to watch the Germans work on the plane, the top of the chimney/smokestack resting on his head continues to dispense smoke, even though there should be no connection to a smoke source. Also, if there were another (hidden) path for smoke to be routed to the smokestack, either Kinchloe's head would block it (again, no smoke), or it would be too hot for Kinchloe to wear it like a hat.
When Klink and Hogan are in Klink's office discussing setting up the casino, clear reflections of stage lights can be seen in Klink's monocle.