Costello's position hanging from the ladder changes from closeup shots to action shots on the highway.
During the climatic chase, the ladder of the fire truck hooks a car and lifts it into the air. A shadow on the front of a building reveals the rigging and crane that actually did the lifting.
There are 2 support structures under the fire engine ladder that are solely there to support the weight of the car and not normally found beneath a fire engine's ladder.
When Lou Costello appears on horseback for the fox hunt, a rope can be seen "tethering" the horse. A voice is also clearly heard saying, "Keep a hold on him, Lou."
When Costello is ostensibly pushing the taxi car horn, both his hands are visible when scuffling with the policeman.
In the undressing scene with 'Arthur Treacher' Abbott calls Costello "Mr. Manchester," although the character's last name is Mansfield.