I don't expect anyone to be able to answer this (or even to care about it) but yesterday, the Trio satellite TV channel reran an episode of Rowan and Martin's Laugh-In that had as its special guests, Debbie Reynolds, Peter Sellers and Johnny Carson. But it didn't say that in any of the TV listings, including the one on the Trio website. This listing read:
Rowan and Martin's Laugh-In – Dan Rowan, Dick Martin, guests Debbie Reynolds, Coslough Johnson and Johnny Carson.
Coslough Johnson is the brother of series regular Arte Johnson, and he was one of the writers on Laugh-In. He wasn't billed on this episode as a guest and I didn't notice him appearing on-camera in it. So why is his name in the current TV listing instead of Peter Sellers? I can only guess that Coslough did a bit part in the episode. Perhaps I missed it (he looks a lot like Arte) or perhaps it's been cut from the current syndication prints…or it could even have been chopped out of the show before it originally aired. Such cuts are not uncommon. Then, the theory would go, when the syndication list was made up, someone went back to the files to get the names of the guest stars, and there was an old contract in there for Coslough, or his name was on a call sheet. Then (still theorizing), that person thought that was the name of some famous performer, better known than Peter Sellers.
This kind of thing happens more often than you'd think. And it wreaks havoc for historians of this stuff.