During the gun fight outside the Alledon Arms hotel, the sign get hit a few times. When Agent 99's gun runs out of bullets, the bullet holes on the sign are gone.
The female client who goes out the window of Max's office supposedly falls to the street below, but she can be seen, through the Venetian blinds, standing outside the window.
Mr. Peter is shot dead inside Max's office, but his body is not on the floor when the Chief enters the office.
In the audio introduction, Barbara Feldon refers to the episode as 'Maxwell Smart, Private Spy' while the title provided on the visual display is 'Maxwell Smart, Private Eye'.
As Max and Miss Markov leave the airport to rush into a cab, the doors they exit from is the same exit that was used later in a later episode Don't Look Back that was the exit to the bank that Max had been framed for robbing with the one armed man. It was also used several more times in the same season. It's been used as the exit to the airport, exit of the bank and exit to various safe houses.