When Hardy yanks at the hose connected to the sink, he is wet. When he comes out of the sawdust chute, there isn't ANY sawdust stuck to him.
As the Boys go into their work area Ollie walks into a plank that's being carried then they both walk into one. In the back ground there's a pile of timber which in the long shot, when the Boys are on their feet, it's just a jumble but when they're sitting down it's a tidy pile.
When Stan and Ollie show up for work at the sawmill, as they enter Ollie is carrying his lunchbox and walks head first into a long board carried by two workers and falls to the ground. This gag is then repeated with Stan in tow after Ollie regroups himself and gets up off the ground. This time they both walk into a long board carried by two more workers. When they both fall to the ground, Ollie is still holding onto his lunchbox. They then scramble quickly to get back up and run inside before the next board goes by. Ollie still has his lunchbox in his hand. Midway thru the shot though there is a cut in the scene and Ollie now has no lunchbox in his hand. This is so he has to go back and get it. Ollie should have left the lunchbox on the ground when he fell down for the scene to read correctly. Not keep holding it in his right hand and running inside with it only for it to magically reappear on the ground behind him.
When Stan planes off a strip of Ollie's overalls, the amount of debris on the table changes and the pot of glue moves next to the saw as Ollie bends over the table between shots.
When Ollie has his hands trapped in the window frame his overall straps slip down the n they're back up again.