Sybil takes a bath because she got milk in her hair -- but her hair is clean and dry when she gets out of both the bath and the shower.
When Buster climbs onto the roof, the ladder is leaning against the front of the house, but when he climbs back down, it's leaning against the side of the house.
The piano changes between when it is delivered (flat back) and when Buster tires to bring it into the house (typical uptight piano back).
During the spinning-house sequence, whether the windows are open or shut is inconsistent. For example, Buster walks past Sybil and two other women who are in the kitchen next to an open window and goes out through the door next to the window. When he steps outside, the window is closed.
Buster drops his jacket untidily onto the floor when nailing the carpet but it's neatly folded up when he cuts it free.
The directions to the house explain it should be constructed according to the numbers of the crates; but Buster already has the walls up when Handy Hank changes the number on crate 1.
When Buster steps out of the second-story bathroom door, the ground he falls onto gives under him, revealing that he's falling on a sod-topped hole full of straw.
A deliberate reveal: at 13:45 the cameraman covers the lens with his hand as 'the bride' gets out of the tub. Breaking the 4th wall as a joke.