The door of a house they're trying to get in is locked, so they decided to break the entrance door by diving to it, and the guy doctor worried about her safety tells her "back up".
Usually "back up" is for "supporting or saving something", but in here it is translated as "back off", so is it sometimes used as "back off" or is it mistyped in this manuscript? I think I heard "back up" or "back off" not clearly.
Mel - Do you want me to do it?
Doc - Yes!
doc- No, no, no, no, no, no! I'll do it. Come on. I'll do it. Back up, please.
Long before there were computers, there was a phrase 'back up'. It means to move in reverse. It is often used in describing how to maneuver a car. The woman was at the door trying to open it. They need to break it in, so the man wants her to back away from the door so he can get a run at it.