An episode of It Takes a Thief (1968) titled "The Scorpio Drop" in which star Robert Wagner starts the Cold Open with "This is the city, Washington, DC. My name is Mundy...I'm a thief." Oddly enough on May 5, 2012 this episode aired on Digital station Antenna TV directly after an actual episode of Dragnet, without even a commercial between the Universal logo and the start of the parody.
MAD once featured Dragged Net! (the radio/original tv version) and Dumbnet - A What IV Production (the 60s/70s version).
An episode of The Monkees features Peter say, "Hey, its time for Dragnet! Anyone got a tv?" This shot is currently (May 2012) being used in an Antenna TV ad, which shows both programs in their line-up.
Seinfeld featured a character called Mr Bookman, a library official who behaved like Joe Friday. Another episode had Kramer channel a Joe Fridayish Inspector in order to get a stolen statue back from a cleaning man.
In the episode of The Simpsons entitled "Mother Simpson", Friday and Gannon investigate the return of Homer's long lost Mother, forced underground after a sixties protest incident. Harry Morgan voices Gannon.
The story you are about to see is a fib. But it's short. The names are made up, but the problems are real.
A Looney Tunes Porky and Daffy cartoon called Rocket Squad is a straight-up parody, set IN SPACE! , where Daffy Duck plays "Sergeant Joe Monday". The twist is that the "Where Are They Now?" Epilogue shows him and his partner being arrested for wrongful arrest.
One The Tonight Show clip features Jack Webb parodying himself as he and Johnny Carson talk in a Dragnet style tongue twister - The Case of the Copped Copper Clappers.
In L.A. Confidential, Jack Vincennes is the LAPD's advisor on the show "Badge Of Honour", which is clearly a DragnetExpy - one of the cast uses "Just the facts", with the implication that it's a recurring phrase in the show.
Keep Circulating the Tapes: Much of the radio series dropped into the public domain. As a consequence, several hundred episodes are available for download from miscellaneous sources — for example, at archive.org in both ZIP-archive and single-episode formats.
Episode 57 ("The Big Bomb") is a remake of Episode 7 ("Attempted City Hall Bombing") with minor edits to accommodate a different police chief and make room for the sponsor's advertisement.
While the TV and radio series were airing concurrently, Webb would occasionally lift the audio track from a TV episode and use it as a radio one (for instance, the Christmas episode "The Big Little Jesus").
Keep Circulating the Tapes: Since just about all of the 1950's TV series has come into the public domain, entire episodes can be seen on YouTube. However, not every episode is available at this point. 47 complete episodes are available from the 1951-52 through 1954-55 seasons but only a total of 12 are available from the rest of the show's run (and seven of those are from the 1955-56 season).
Many radio episode scripts were adapted for television, including the aforementioned City Hall bombing episode (Season 1 Episode 1: "The Human Bomb").
The Christmas episode with the "theft" of the Child Jesus statue aired during the original TV series (where it was the first-ever TV episode to be filmed in color) and then was redone for the '60s remake.
Webb wanted Ben Alexander to return as Frank Smith in the revival series, but Alexander had already committed to Felony Squad, so Webb turned instead to his friend Harry Morgan and Bill Gannon was created.
Jack Webb was working on a second Dragnet revival in 1982 with five scripts completed. With Harry Morgan committed to Mash and its After ShowAfter Mash, Webb would have changed partners once again, this time to a character played by Kent McCord (although it's unknown if it would have been his Adam-12 character or a new one).
One of the Lassie dogs appeared in the purse snatching dog episode - it clearly has the distinctive facial blaze absent in most collies but present in all the Lassies.