I just manipulated those automatic doors in the Zoo level to get the cart, but the door shut again before I could get back out. I can't seem to manipulate the lever I can see through the bars, and it seems there's no way out. Do I need to restart?

edit: I just quit to main menu and then hit continue, this put me back at the car with the cart still in my inventory. that CAN'T be how it's supposed to work