When Boris initially shoots out the windows, while Ivan is trying to put up a blanket, there are no holes in the wall behind Ivan where the shots would have ended up.
After Ivan knocks out the window, you can hear the camera operator stepping on the broken glass as they move for a closer shot.
In his taped message to the major, the commissar explains he is immune to the wine's narcotic effect by having drunk gallons in the past. But as this is occurring in Europe, liters would be more likely since the US gallon is not used as liquid measure there, especially with wine.
After listening to the taped message, Kuchenko smashes the recorder. It then proceeds to play at what sounds like an accelerated speed although the reels are moving at the normal speed.
When Commissar Vassiloff is explaining to Boris where the surprise is and how it works, there is an off camera noise that causes the actor to stop and then restart his dialogue.
When Boris is shooting at the Major as he is running out of the room, it shows a bunch of bullets strafing the apartment wall as he's exiting. Boris is shooting the Major from the other apartment on the opposite side of the building, so it would be an impossible angle to shoot the Major as he fled into the hallway as he left the room.