When Mannix is in Saunders' apartment, he's wearing a plain white shirt with a royal blue tie. Then when he answers the phone in his car right after that, he's now wearing a white shirt with blue stripes and a dark blue tie. Then when he goes to Reynolds' house right after that, he's wearing the plain white shirt with the royal blue tie once again.
When Mannix is in Stella Carter's (Beverly Garland) apartment, she puts a cassette tape in the cassette player. The music starts playing immediately, without her pressing the play button.
When Mannix and George Fallon enter Bill Saunders' apartment, Mannix notices that the lid to the cassette player is open. The back of the cassette player is facing the camera and it's obviously not connected to any stereo equipment so any tape played could not be heard.
Mannix says the accident happened "a couple of weeks ago," but his mouth says "a couple of months ago."