---The actor who played one of the detectives that arrested Venus in the episode about the jewellery robbery was also Ivan the Russian who wanted to defect in a different episode.
---The actor who played Del Murdock in Del's stereo and sound also played Johnny's ex-wife's husband in an episode near the end of the original series.
---The actor who played the federal bureaucrat in the "Ivan" episode, I think, was also in the episode when Johnny returns to the station.
Correct on all three! Michael Pataki, Hamilton Camp, and Sam Anderson, who played four different characters on the original show plus one on the 'further adventures' series.
Also:
Daphne Maxwell (Reid) - Jessica Langtree the jewellery thief herself, and also the TV co-host of 'Real Families'
Michael Fairman - shop owner who hassles Les in the turkey giveaway remote, and Buddy the veteran pilot who flies the bi-plane; he was also a writing partner with Richard Sanders on several episodes (including the aforementioned Veteran's Day episode)
Michael Des Barres - 'Dog' from Scum of the Earth (original series), and morning man Jack Allen in the new series
Thomas Calloway - 'Steel' the maintenance man and Jennifer's love interest (original series), a lecherous lawyer putting the make on Mona in the new series
Character actors Hugh Gillin, Don Diamond, and Alice Nunn also had two different bit parts on the original series.
FYI, if you are a WKRP die-hard fan, the blog
http://wkrp-relived.blogspot.com/ is a great read.
GDAMTGNBY