With three years to work on the book, a lot changed from when "Be More Chill" first premiered in 2015. However, some things never change.
Michael Canonically Has Two Moms
Two River Theatre (YouTube)
https://www.youtube.com/watch?v=EdvPDpPoR6U
Thanks to the BMC Fandom sharing and promoting dozens of their own theories, Michael now has two mothers. Upon seeing that Jeremy and Michael have "boyf" and "riends," respectively, written on their backpacks, Michael says "My moms would love that." Yay for anyone who supports this now canon theory!
Ecto Cooler
summerstarkiss.tumblr.com
Since Crystal Pepsi made a comeback and Michael getting that from a dealer in the back of Spencer's Gifts would just be creepy, Joe Tracz (book writer for 'Be More Chill') has Michael buy vintage Ecto Cooler instead. "It tastes like GHOSTS," according to Michael.
Reggae? Reg-NAY
Two River Theatre (YouTube)
https://www.youtube.com/watch?v=EdvPDpPoR6U
Back to BMC theories, fans have speculated many reasons for why the reggae theme returns about halfway in "More Than Survive — Reprise." Well, Joe Iconis (music/lyric writer) changed the instrumentation to be plainer, so no more obscure theories.
Loser, Geek, or Whatever
NewYorkTheater.me (YouTube)
https://www.youtube.com/watch?v=uIgAy6n32Hs
One addition to the off-Broadway production is the new song that Jeremy sings as a solo at the end of "Upgrade." Seeing this song performed live at the first preview was one of the best moments of my life. Will Roland does an amazing job delivering this relatable song, and all I can say is check it out here if you haven't yet.
Burning Cards Has Burned Out
Ghostlight Records (YouTube)
https://www.youtube.com/watch?v=WaMRF8ucGJo
The heart-wrenching scene of Michael burning old birthday cards and ticket stubs from Jeremy was cut from the Off-Broadway production. But see the next point for why it's almost worth it.
Mr. Heere to the Rescue
Two River Theatre (YouTube)
https://www.youtube.com/watch?v=EdvPDpPoR6U
"The Pants Song" used to be about Michael trying to get Jeremy's dad involved in helping Jeremy. Well, not anymore! The "Two Joes" flipped the script and instead, Mr. Heere goes to Michael's house to get him involved in helping his friend. No more Michael telling Mr. Heere to go to Kohl's to buy some pants; no, now it's a hilarious scene with Mr.-Heere-turned-drill-sergeant telling Michael to "SAY IT LIKE [HE] MEANS IT" when asked if he's ready to help Jeremy. That's the spirit!
Pitiful Christine?
Two River Theatre (YouTube)
https://www.youtube.com/watch?v=EdvPDpPoR6U
The lyrics to "Pitiful Children" changed drastically, instead focusing only on "squipping" Christine rather than Jeremy's friend group as a whole. The latter half of the song is pretty much the same, but the beginning is all The Squip trying to convince Jeremy that all of this will help Christine and help him get her. The dance scenes and costumes are just as awesome, however.
Despite All These Changes...
BuddyBroadway (YouTube)
https://www.youtube.com/watch?v=jXSuv5g_uIY
The show is still the fun, spooky, thought-provoking show it was back when it premiered in 2015. The show has picked up traction in the past few years and developed a fanbase that spreads worldwide, and there's no doubt that this show has big things in store. Humans may have stopped evolving, but this show hasn't, and it just keeps getting better and better.