When Tim is passed out drunk on June's bed, the hair on his forehead disappears and then reappears between shots.
The "Himmelweiss" portrait -- straight when Tim first hangs it over the dresser -- is suddenly askew in the following shot, and again straight in the shot after that.
In the car scenes after Tim and June pull away from the Standish Arms doorman, Tim's left arm is inconsistently atop the driver's door, then inside the car as they converse.
At the Lakeside Lodge counter, Dr. Timothy Sterling asks June Cameron to lower her voice so he can hear on the phone. The phone wire is draped over the far corner of the counter. In the next frames, the cord is across the whole counter.
The nose on the doctor's head is broken off, yet when his visitors are later inspecting it, the nose is back. In between the doctor had absolutely no opportunity to repair or replace it.
A key plot point is the fact of only one bedroom. However, the spiral staircase obvious in each apartment strongly suggests there is another room upstairs.