When the Stooges first see the supposedly free car their reflections running toward it are visible in the door. But in the next shot they are standing still.
Curly clearly has oil on his face and eyes when he first meets the sisters... even though the pump hasn't erupted yet.
When the three stooges start fighting the crooks in the car, the three stooges are in the front seat of the car and the crooks in the back seat. Next scene the crooks are in the front seat and the three stooges are in the back seat.
While repairing the pump, the long bar the Stooges use to loosen it backfires, knocking all three to the ground. When they land face-first you can hear a distinct fart.
The padding under Moe's coat is clearly visible in the scene where the saw hits him in the stomach.
When Curly comes up through the wagon opening and gets hit by the tossed wood a hand can be clearly seen dropping the wood on Curly's head.
The 3 men who are collecting the deeds are shown sitting in their car.
You can see a pair of legs, probably belonging to a camera man, to the far right, in the reflection of their shiny black car.
At about ten minutes, when Curly is dancing the Window Jenkins through the door, you can hear the crew laughing at Curly.