This movie has been well known for its star teaming of two big Hollywood action heroes, Burt Reynolds and Clint Eastwood. Reynolds would later play a character called "Clint" in Standby, whilst to date [July 2013], Eastwood appears to have never played a character on-screen called "Burt".
Though filmed in color, the Warner Brothers logo at the start of the picture is displayed in black-and-white, as is the opening shot, bar for the title card of the film's "City Heat" title, which is shown in bold red.
In the scene where Spear gets into a shoot-out with the thug in the hallway and stairwell, he shoots the thug a total of eight times, all in the upper chest area. However, later when he and Murphy are examining the bodies in the morgue, there is an overhead shot of the same thug and he has no upper chest wounds of any kind.
The doctor tells Lt. Speer that Ginny broke her arm when she was hit by the car. However, when she reappears at the end of the movie singing in the club, she is not wearing a cast or showing any sign of injury.
This first time Murphy (Burt Reynolds) visits his apartment, he switches on his 1930s era radio, which instantly begins playing music, as a modern one would. This is incorrect - a radio of that era contained vacuum tubes, and it would have taken the radio several minutes to "warm up" before any music could be heard.
Mike Murphy: [the phone rings again after Murphy hangs up on his girlfriend, but Murphy makes the mistake in thinking it is his girlfriend calling him again]
Ok, I'll come over and buff your body and put a nice glow to your cheeks.