Different size/shape of the ragged hole in various inside/outside shots of the torn metal mesh in the door as Max is ripping his way through the door to free Jaime and Callahan.
The carnival grounds are shown to be still fully furnished with the traditional festive regalia of active use. If the carnival was shut down for the winter, the fabric tents, awnings, and other cloth-based furnishings would have been taken down and stored away, out of the wind and sun that would needlessly batter and deteriorate the items during the off-season, and cause them to be destroyed more quickly than necessary.
There was less than a minute of conversation between the villains and Callahan, so there would not have been over half of the C-90 cassette tape to rewind in order to listen to the conversation.
Max is clearly seen to momentarily let go of the slipper during his tug-of-war with Jaime over it.
When the two goons looking for Max stop, and Max comes up right beside them, the one on the left is visible when the camera is in close up on Max. When Jamie snaps her finger and the two take off running, the shot goes back to the close up of Max - and the guy on the left is still visible in the shot.
The villains wanted to sell Jaime "alive and undamaged", so they would not have tried to shoot her with bullets; they would just have used more tranquilizer darts.
While searching for Max after his escape, one henchman remarks their dart guns should knock him out for a week. Problem is, they had previously shot Max with the same darts which only incapacitated the dog for a brief time.
Agent Fowler says, "Jaime must have heard the tapes," but there was just the one cassette that Oscar played in the adjoining room.