When Karen is about to set up Major Karp, she is seen rubbing lipstick to her right palm to rub on him, but when Major Karp puts Karen's coat on her, she turns toward him and applies the lipstick with her fingertips.
After Klink serenades Karen, they each have a glass of wine. Karen spills hers on Klink, and creates a visible stain on Klink's left lapel, visible from over Karen's shoulder. When the view shifts to show the two of them from the side, and Klink decides to change out of his jacket, the stain on his lapel is gone.
Schultz calls the prisoners out for a special formation, during which Klink announces that new security protocols will be started at 1600, which would put a guard in each barracks 24 hours a day. When Hogan and the gang go into the barracks to discuss plans for getting the general back to London, Hogan looks at his watch and says they have two hours before the new security system starts. Therefore, the formation took place at 1400 hours, or 2:00 PM. Given the length of the shadows the men cast during the formation, there is no way it was actually 2:00 PM.
After Klink serenades Karen, and Schultz serves the wine, Klink 'hints' for Schultz to leave. Schultz goes into the bedroom, which makes no sense. He should have gone out through the other door - the kitchen.
UPDATE: This is not a goof. Moments after Schultz goes into the bedroom, Karen "accidentally" spills wine on Klink's jacket, then suggests to him, "Why not have Schultz dry it for you?" Klink then goes into the bedroom. That's where Schultz has already gone.
UPDATE: This is not a goof. Moments after Schultz goes into the bedroom, Karen "accidentally" spills wine on Klink's jacket, then suggests to him, "Why not have Schultz dry it for you?" Klink then goes into the bedroom. That's where Schultz has already gone.
On the tree that the General is shooting behind, white paint has been put on the trunk to simulate snow. It is in an irregular pattern that snow would not form on a tree trunk.
After Karen puts the lipstick on Major Karp, and they get caught, Karen leaves. Frau Linkmeyer approaches Major Karp and says, "How could you? How could you?" As she turns away from Major Karp, she calls out, "Albert, where are you, Albert?" During that line, a very light shadow of the microphone can be seen sliding across the wall behind them, disappearing when it reaches the breastplate mounted on the wall.
Production lights are reflecting in Klink's monocle in several scenes.
After Hogan complains to Klink and Gertrude Linkmeyer about the guards being posted in the barracks, Klink never indicates that they will be removed, yet Hogan and Baker are immediately down in the tunnel calling Karen. They would not have been able to do this if there was still a guard in the barracks - even if it was Schultz.
Klink speaks without a German accent at one point.