Battlestar Galactica (2003) to The Bob Cummings Show

Battlestar Galactica's pilot had a scene showing a Firefly class ship flying over

Weyland-Utani is a client of Angel's Wolfram & Hart and also the company that made some of the weapons used by Firefly's Malcolm Reynolds in the Battle of Serenity

Angel was a spin-off of Buffy the Vampire Slayer.

The X-Files? Cigarette Smoking Man and Buffy the Vampire Slayer's Spike both smoked Morley cigarettes.

The mugshot of Malcolm T Wiggins from the X-Files episode "Titonus" appears on the wall of a police interrogation room in the Veronica Mars episode "Leave it to Beaver." Also the fictional car rental company Lariat where Mulder & Scully always rented their cars was featured prominently on the Veronica Mars episode "Rat Saw God."

In an episode of Veronica Mars, Veronica's fortune cookie had the numbers that won Hurley from Lost the lottery.

The airplane that crashed and strand the cast of Lost was Oceanic Airlines Flight 815 also featured on Diagnosis Murder.

Mannix returned to TV on an episode of Diagnosis Murder to solve an old unsolved case with the help of Dr Mark Sloan.

Here's Lucy's Lucy Carter and Mannix's Mannix are held hostage in an episode of Here's Lucy.

Here's Lucy's Lucy Carter was visited in two episodes by The Bob Cummings Show's Bob Collins.