Stupidity: Mrs. Doubtfire used the bathroom without first locking the door, enabling Chris (or anyone else) to walk in on her. A man who is dressed as a woman and doesn't want anyone to find out would make sure the bathroom door was closed and LOCKED. (01:07:09)
Suggested correction: Daniel is in his own house, and he may be used to using the bathroom without locking the door. Besides, he probably only thought he was going to be in there for a short time.
Stupidity: At the end of the film, the Rehabs recruit gang members and give them all kinds of guns from shotguns, handguns, and automatic weapons. The cops and deputized citizens have similar weapons. But for all the shooting, not one gang member is hit and only one citizen appears to be shot (aside from the three blown off the building roof by the Rehab tank.) I don't think anyone has any bullets.
Stupidity: If Nick was desperate enough to have his door locks changed after Darian has been stalking him, then why does he leave his door wide open and allow her to come in when he discovers that Amy is in the hospital over the phone?
Stupidity: There is no way Mr. Mertyle did not hear the fence in his backyard crash to the ground; there's also a likely chance he could hear his dog crying and Smalls saying the dog is hurt. Even if he could ignore the sounds of other attempts to try to get the ball back; with the fence coming down where his dog lives and the chances of an injured pet it seems far too unlikely he wouldn't have rushed straight to the backyard hearing this.