Updated December 2022 to include a note about the movie Die Hard.
Often when watching movies, I will simultaneously look up the background of them on Internet Movie Data Base (IMDB), or, if the film has guns, the Internet Movie Firearms Data Base (IMFDB).
I did so recently when I was rewatching the 1995’s excellent Heat, starring Robert De Niro and Al Pacino. It has a lot of interesting firearms in it, and I wanted to learn about them.

What I found, however, was an interesting mistake, and one that I see over and over in movies about crimes and cops: a shot showing us a signature rifle muzzle device also happens to show us two police scanners. One of them, the top one, is a Radio Shack Pro-2030. The display on it reads 000.0000, meaning it was never programmed, or it was reset at some point and never reprogrammed. Either way, it isn’t working.
The lower scanner, a Radio Shack clone of a Uniden 500 UBC9000XLT (Probably the
Realistic Pro-2036.), displays 470.5375, which is the correct frequency for Los Angeles Countywide police dispatch.
In the movie Die Hard (IMDB), (IMFDB), on the other hand, the TV reporter, a one-dimensional character played by William Atherton, is on the phone when he hears a panicked police call from an LAPD sergeant played by Reginald VelJohnson. I assume this scene takes place in the fictional TV studio, since there do seem to be at least a couple of reel-to-reel audio tape decks in the background, but the scanners supposedly picking up the call are junk fished out of the back of the props department.
Two of the radios appear to possibly be Radio Shack / Realistic Comp-100s or maybe similar Bearcats. Both are early 1970s tech, and use crystals to set each frequency. Neither of the radios in the scene appear to be receiving anything, though, since the red LEDs on the front panel continue to track and don’t stop on a channel. The other radio is hard to make out, but might be a higher-end communications receiver or all-mode amateur radio transceiver. It appears to display something like 145.890 Mhz, which is an amateur radio frequency, not a police frequency.

Update, summer 2024: apparently, movie studios with multi-million-dollar budgets can only afford to buy a few scanners, because as I was watching a YouTube item about The Fast and the Furious, I saw the same 10-channel, crystal-controlled Radio Shack police scanner of 1970s vintage.

Also, the characters repeatedly interrupt each other while talking on two-way radios, which we all know is impossible since you can either receive or transmit, not both at the same time.
For what it’s worth, the movie with the most accurate and believable radio communications that I’ve seen is End of Watch. Jake Gyllenhaal clearly studied and practices with real police and how they use radios for this film. Props.
Heat is by far the best, most interesting, and probably the most realistic, cop movie ever made. It seems to understand the psychology of being a police officer very well. My favorite scene is the one where Pacino interrogates the guy in the nightclub, a mixture of intense grilling, yo-man bullshitting, and pure joy. You can tell Vincent loves his job and loves doing this shit. But he’s also probing deeply for information. Multiple levels there. And in every scene.