During production of the first season, only Kristen Bell and Ted Danson knew about the twist from the beginning. Kristen recorded a video of the remaining cast members being told about the season 1 reveal. Their reactions are face-holding shock from Jameela, surprised giggling and hiding behind clothing from D'arcy, a giant "Oooooooh!" from Harper, and Manny just... flailing and twitching as he tries to process everything.
Doubly funny when Michael Schur related in an interview Manny initially worried the meeting was going to involve them being fired.
Season 1's gag reel is hosted in-character by Trevor with series appropriate meta-ness (negative points for hosting a party about making a TV show, for instance) as well as the gags and bloopers themselves. Standout moments include:
The different improvisations Jacinto and Carden did; specifically, when Jason tells Michael what his vanity plate says, how he died ("stingray jousting accident" and "escaped zoo animal rampaging through a mini-golf course" are both present), and when Janet misidentifies a basketball (one standout: "Look, Michael, a witch... Burn her.").
The official Youtube channel livestreamed and uploaded a five-hour video of what Janet does in her void. A good 90% of that video comprises Janet just happily standing there in silence (with the occasional change in arm position and camera cut), waiting for someone to ask for her assistance. Whenever she is needed, she bings out until she's done. Which leads to the other 10% of the video—an empty, unoccupied white void.