When Healy says, "Happy Thanksgiving, Piper," before leaving the SHU, the reflection in the window shows Piper turning around and walking away. In the next shot, Piper is still facing the window.
When Piper and Alex are hanging up the going away banner for Tastee, it goes from taut to sagging a few times between shots.
When Alex comes out of her shower to find her glasses broken, both lenses are cracked. You can see this in both the shower scene and later when she talks to Nicky as she tapes the two halves of her glasses together. But later when Alex is talking to Nicky in the cafeteria the tape is considerably neater and one lens is missing, even though Nicky mentions that the only way to get a pair of glasses fixed is by getting a prescription from someone on outside [of the prison].