When the portrait photo of actor Raymond Bailey (Gild) is shown, it is of him without his toupee' (which he variably wore or didn't wear in his roles). But when Gild is finally located, Raymond Bailey appears wearing the wig.
None of the characters ever mentions anything about the wig.
This is either an error, or perhaps, in an effort to disguise himself, the character decided to wear a wig.
It's quite possible that during production, the wrong photo was used for the closeup shots of it. These closeups of Gild's photo were then not likely seen by the actors during production.
This is an old small screen TV show, and it's also possible that the production thought it wouldn't be noticed (?).
One male actor is not credited even although he is involved in at least five lines of dialogue with Walter (Robert Horton). This is at the beginning of the show before Walter goes in to see his boss, Regis.