When the father and the three stooges leave the crook's room, the father is holding the bonds. When they re-enter the crook's room after seeing part of the gang in the corridor, the father is no longer holding the bonds and the bonds never seen in the rest of the film.
During the "Home on the Range" song near the end, when Curly goes to hit Moe in the face with custard, he completely misses on the first try.
when the boys are standing in front of the grocery store -you can see the Kix Cereal boxes turned up side down in the left window display.
When Larry tries to open the apartment house door, he says its locked, so they decide to break it down. Then, the door can be seen opened just a tad so when they rush it the door opens.
When Curly throws the light bulb on the basement floor, the light is still seen on for a few seconds.
When the Stooges are hiding from the detective underneath the awning of a grocery store, the Kix cereal boxes are printed upside down.
When Moe is hit with cream from the custard pie, he closes his mouth, but is still heard singing with Curly and Larry.