Adam-12 to Mission: Impossible (1988)

Emergency! had a crossover with Adam-12 to find a boy who ran away from the hospital.

Both feature the fictional Trans Global Airlines

Diagnosis Murder's Dr Mark Sloan was defended by Matlock when Sloan was accused of murder

Diagnosis Murder's Doctor Jesse Travis's father is a spy that someone is trying to kill. One of the possible suspects is the original Mission: Impossible's Cinnamon Carter.

Mission: Impossible was continued 22 years later