Elaine's body changes position between shots when seen in the ceiling mirror in Mona's bedroom.
When Toni opens the pot of pink paint, it's full. When she throws it at the wall it's more than half empty.
When Beau is sitting in the bathtub of his flat, before he notices the man above him, there's some sawdust on his eyebrow. In the next shot, it's gone.
When Mona falls on the glass table, the view from above her shows her left leg across the edge of the table. In the next shot from behind Beau, the leg is not visible.
You can see the mic pack of Tina in her back in the painting scene! At certain angles it disappears and in others it appears back.