Well, I've finished watching all five episodes today, though there's still some bonus features I haven't watched yet (audio commentary, Goodbye Mr. Hooper, How to Be a Grouch with Caroll Spinney's video image). It's all great.
When watching episode 1446, I was surprised to see that an old recording was used when Big Bird sang ABC-DEF-GHI. It's interesting to hear the season 1 Big Bird voice over visuals of season 12 Big Bird, especially when his better-known voice is heard for the rest of the show. Even more surprisingly: They used the recording from the first broadcast as opposed to the original record recording (he contemplates asking Bob or Gordon, which he did in the original version but not the record version). Sure, there are other instances where remakes use earlier recordings, but this one seems to stick out more (though after watching the 1991 version of I Love Trash so much on The Best of Friends, it also feels a little odd hearing 1970 Oscar on 1991 Oscar, especially with Oscar's spoken-word introduction coming right before the old recording).
Watched episode 1316 last night. I was surprised that Maria was celebrating her 21st birthday. When she first appeared in season 3 she looked a lot older than 11 (actually I'd say when she debuted she looked closer to 17). Maybe it's a case of "dawson casting", a term used by TV Tropes to refer to actors who are much older that the characters they play are supposed to be.
Also in that episode, when Oscar's in his traveling can, his legs look longer than they do in any other "traveling trash can" scene that I've seen, and the can looks bigger as well. In this episode it seems we never see Oscar's legs out of the trash can when he's with the rest of the cast (when he walks away from Gordon we don't really get a good view of his legs).
It's interesting comparing the amount of classic cuts to the amount of clips in the 40th anniversary set. On that release, seasons 1-5 and 11-15 got heavy focus, while it seemed to rush through seasons 6-10. On Old School Volume 2, each season was represented with at least 9 bonus clips (counting the closing credits crawl), with season 6 being the only season with 6 bonus clips, and the 40th anniversary set had 3 clips for seasons 6 and 9 (well, you could say that season 9 had 4 clips, since it's technically two hawaii clips, but three chapter stops) and only 1 for the other seasons. Volume 1 had an uneven mix of clips for each season, but season 3 had the most, and on the 40th anniversary set season 3 got the least amount of clips, while both volume 1 and the 40th anniversary set seemed to be a little more even with the amount of clips per season. And on the 40th anniversary set seasons 11-14 had 4-6 clips per season, with season 15 having only two. And this set has the least amount of bonus clips.
Hmm, I'm starting to think, maybe next time all of the bonus clips should be on disc 2, instead of spreading them among discs.
Noticed that this time around, the trademark credit for Kermit only appears at the end of the episodes that actually have Kermit. Previous volumes included that credit on all episodes, even ones that didn't. I also find it weird that they had to blur Kermit's face from Caroll's shirt in the behind-the-scenes footage, since he is present on this set (Kermit's face wasn't blurred in behind-the-scenes footage on the 40th anniversary set, while other Muppet images were).