The scene where the monster first "steps" out of the house, "she" rips the curtain rod down and breaks the window panes in the door before yanking it open to make "her" escape. In the scene where Trudy opens the door, seeing the monster for the first time (as it was returning) the curtain rod, glass and door are undamaged.
During the scene when Sandra Knight as Trudy Morton opens the door and faints because she is frightened by the monster, she falls to the floor. After she is supposedly unconscious she very obviously lifts her arm and places it on her hip. Then once the camera moves off her and returns she is in a completely different position than she was previously (she was originally on her left side with her back to the camera, and she's now shown on her back)!
At around 19 minutes Dr Frankenstein's hand changes between on the door frame and not on the door frame between shots.
At around 1:22 Johnny and Trudy run through a locked door without even having the key to unlock it.
With the introduction of the first scenes of the beat group at the poolside, the lead instrument heard is a saxophone: which is not an instrument shown (being played) in the group.