One thing I've been curious about is, before this was even shot, how close were Frank Oz and Bill Barretta? I've heard about Frank referring to Bill as "the new guy", but it seems they didn't work together on many projects. Most of the major productions the two worked on (Muppet Treasure Island, Muppets Tonight, Muppets from Space), Frank's availability was a bit limited, with him primarily only doing voices and only being on set for a few days. In the case of Muppets Tonight, I think he was on set performing his characters a lot, and it's clear he was there for the main taping dates for some episodes (don't know if he was available for all days of shooting or if it was on par with how much time the guest stars spent on the taping dates), but I think a lot of sketches with his characters were shot on a single day and inserted into multiple episodes (though I've mostly heard this from fans online, maybe it's an assumption).
Just because the two didn't exactly work together that often doesn't mean that they couldn't have been good friends regardless (and it seems like Frank still hangs out with his fellow performers, maybe Bill was included among his group of friends through the other performers), but it is a bit interesting to think.