Corrected entry: At the very beginning of the game in 72 Hour Mode, when you make it to the security room after the incident in the Entrance Plaza, Brad tells Otis to seal the door tight, making it impossible to enter or exit the door for the rest of the game. However, in Overtime Mode, which takes place right after 72 Hour Mode, the door is now open.
Corrected entry: During gameplay, Frank will always be holding his camera and only be able to use 1 hand. In the cut scenes, Franks can use both hands because his camera is suddenly on a strap.
Correction: Frank's camera is always on a strap, he just holds it most of the time in one hand. This is how he's able to carry larger items with two hands.
Correction: The Army forces the door open when they arrive in 72-hour mode. You can use this door after that point in the 72-hour mode as well.
Captain Defenestrator