Emergency! to Still the Beaver

Both feature the fictional Trans Global Airlines

Diagnosis Murder's Dr Mark Sloan was defended by Matlock when Sloan was accused of 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 Mary Jane Lewis was originally a character on The Lucy Show (also called The Lucille Ball Show).

Mr. Mooney from The Lucy Show was on Hi Honey, I'm Home!

Leave it to Beaver's June Cleaver crossed over onto Hi Honey, I'm Home!

Leave it to Beaver was continued as The New Leave it to Beaver

Still the Beaver was retitled The New Leave it to Beaver