https://derpibooru.org/2136536

The Best Night Ever is part of Season 26 (1994-1995) of Sesame Street, and thus the season ends with a book closing. The Sesame Street sign and the CTW logo are part of the front cover of the book.

@Background Pony #A2EA
 
Yeah, that’s why Derpy was a non scripted background character without any of the specific scenes like in the rest of season 2. I think they even forgot to edit her eyes like the last half of season 1. It’s also why it has the original intro instead of the one made for season 2.
 
At the time, the fandom was concerned about the show because we heard that Faust left at some point. But Return of Harmony was said to not count since the episodes were postponed season 1 episodes.

@Background Pony #3DA8  
Oh really? Interesting.

Actually if FiM only had one season it would have ended with the Return of Harmony. It was originally created as the season finale but postponed to season 2.