After Superman has pulled the door off the fur vault and left it leaning against the wall, it is obviously beginning to fall forward as he leaves the shot. Following the shot of Superman taking off out the window, it returns to the previous shot but with the vault door safely leaning against the wall.
After Superman tears the safe door off, he leans it against the wall. As he is leaving, it starts to fall over. in the next shot, it is again leaning against the wall.