I don't know why it was held over, since it's a funny show, the first written by Wilson's friend Bill Dial (whose most famous credit on the show is the Thanksgiving episode), maybe broader and more focused on guest-star parts than what came afterward. My favorite line is a throwaway for Venus: "Andy, I think I'll... I don't know, I'll probably go buy a car or something." It's hard to write a line for a character who's about to leave the room for no particular reason; that's a really good one, and like most of the best lines on this show, not really a punchline per se.
In casting notes, John Chappell, who plays the Minister, was cast by Bill Dial as the engineer on The New WKRP, and Suzanne Kent, one of the "Merciful Sisters of Melody," had a busy time on TV that season; she also played Angela in the famous "Blind Date" episode of Taxi (returning for a follow-up episode the year after).
This is the only episode where Herb and Les don't appear. The original idea was that there would be maybe three characters who appeared in every episode, and other characters would rotate in and out like Sue Ann and Georgette on Mary Tyler Moore (characters who were not in every episode but were sort of regulars). However, by the end of the first season, Hugh Wilson decided that all eight characters should appear in every episode.
The song Johnny plays in the opening scene is, as I've noted before, "I'm Down" by The Beatles. Hugh Wilson was a big Beatles fan and would have liked to include more of their songs on the show, but even with the discounted rates the show got, they were too expensive, and their songs were only used in two other episodes. (Second most expensive, probably -- and not surprisingly -- were the Rolling Stones, whose tracks were the first to get removed from the show in syndication.) I don't know about the music at the very beginning; it might be a piece of soundtrack music, but since it was removed in the '90s, it might be a real song of some kind.
Also, there are two versions of this episode, one as originally produced with the main title before the first act, and one that uses the first scene as a cold opening before the main title. This is the original version (unfortunately without the title sequence, but you've seen it).
Act 2 and Tag