When Hubert is playing the piano at the party, he finishes the song with two chords, one for each hand. It's obvious, however, that he plays nothing with his right hand as it's up in the air as the chords are played.
(at around 24 mins) When Wesley is under the decking choking due to the dirt, his mouth is out of sync with his coughs and wheezes.
Marjorie first hugs Bill at the dance and the powder bursts all over her chest. In the next instant as they begin to dance Marjorie's front is clear of powder.
George moves his dinner plate toward him twice.
The doorbell rings just as Stella finishes putting rubbing alcohol on Marjorie's leg. Marjorie moves her skirt down to cover her leg, then does so again in the next shot.