Also a character error, besides continuity: after opening the windows, Mannix returns to examine the man "resting" against the open oven door. He his holding his handkerchief in front of his face (ever since he walked in), but now his nose isn't covered. When the camera angle cuts to the man who just entered's P.O.V., then Mannix has the handkerchief higher up on his face and is covering his nose, all over again.
As Mannix and Mart Gray fight near the end of the episode, in the medium shots it is clear that a stuntman and not John Considine is doing the fighting.
As Joe Mannix is driving his client away from her apartment, several banks of bright studio lights are reflected in the shiny paint on the driver's side of Mannix' vehicle.
At about 22:40 the camera rig and reflector panels are visible reflected on the housing of Mannix's side view mirror.
When Joe Mannix goes to question the cab driver who gave a ride to the mysterious man shadowing his client, the reflection of the boom microphone appears twice in the rear window of the cab as he and Mannix talk.