During the exterior shot of Mannix's car headed to Tony's office there were two vans fairly close behind, but the interior shot only showed a '59 Buick fairly distant.
Mannix is soaking wet on all of the final scenes, but on the very last shot, he's dry -- albeit with messed-up hair to apparently simulate having been drenched.
When the guard first talked to the guys upstairs to announce Mannix's arrival he was talking into an ordinary transistor radio, but later he used a regular two way radio.
It's a very sunny day on all of the shots outside of the tower. But when the camera is pointed toward the windows from inside the building, it's gray and overcast outside.
Mannix is told that there is only one elevator working, making it the one Tony would have had to have used to get up to his office. The car should have been on Tony's floor, but it was already back on the ground floor.
Once Mannix arrives, Tony has a hurt leg, leaving Mannix to handle the entire situation by himself. This is not consistent with how the burglars took him down. --- INCORRECT: When paying attention to what transpires on the roof, at the end, Elliott evilly acquiesces when Mannix remarks to him something to the effect of: "I see your legs no longer hurt and you can walk fine/it was all for show".
Mannix uses 3 different 1974 Camaros in this episode. While driving to the Warren Building with Tony Elliot he is driving a fairly stock Type LT (badging on the "B" pillar). Upon arrival at the Warren Building he is still driving a Type LT but it appears that the chrome drip rail trim extends on to the "B" pillar. This configuration was not available from the factory. Later when Mannix uses the car as a battering ram in the parking garage, no Type LT badging nor the extended trim are present.
Peggy isn't fake writing; she's using shorthand. Every secretary of any quality in the 1960s and 1970s had to be proficient in typing and shorthand. Joe Mannix would dictate letters to her and she would type them.
When Peggy takes the message that Mannix is awaiting, it clearly can be seen that her hand simply glides over the paper, pretending to jot down a message but Gail Fisher is not even bothering to draw waves or curls in lieu of cursive (alphabet letters nor shorthand), nor lifting the pen if she were writing in print or shorthand.
At 9:00 minutes, we get a wide shot of Joe and Tony in the car and they're being tailgated by blue and white van. We then go to a hood camera two shot of Joe-Tony and there's no van in background. Nothing.
When telling Joe about the fishing trip, Tony says he bought a bunch of new flies. But, when Joe is practicing casting in his office, he is not using a fly fishing rig. Joe takes that rig to his car. Then, in the car, Tony says he forgot the flies in his office. It is highly improbable that the two of them would be going on a fishing trip and the two of them do different types of fishing.
Overdubbing of Bill Bixby's voice in the bar when he tells Joe what time they're going fishing.
At the 30:00 minute mark Mannix is running down the buildings stairwell. Just as Mannix reaches the bottom the shadow of a cameraman's head appears to the left of the screen leaning in to check on Mannix.
At about 30 minutes,14 seconds when Mannix is racing down the staircase a shadow appears in the left corner.