When Moe and Larry pick up Curly to use his head to break through their cell wall; just before they hit the wall, the man changes to a man with hair (probably a stunt man).
When the Stooges drag their father away at the end, you can see the stunt double's face.
When Larry and Moe are trying to get through the gate using a hammer and chisel just before Curly hits the chisel Moe bumps the gate and it moves open slightly; but is back closed tight when Curly actually swings the hammer.
When Moe and Larry chase Curly into the street after the haberdashers, nearly run over by dad's gold digger, Curly changes to a man with hair (probably the same stunt man reported before).
When Larry blows the oil through the tube Moe is holding, you can see a hose connected to Moe's sleeve, where the oil originally came from.
When Moe throws his socks onto the bench for Larry to wash, you can see the string attached to them to make them stand up.
It's never explained why the boys are in jail at the beginning of the short (though one might presume theft, as Curly steals silver goblets and a tray at the wedding and also doesn't appear to pay for a hat he likes when the boys are shopping for new clothes).
When Moe reads the letter from their mama he says "old" oil land. The letter just states oil land.