Acting for Two: Players with the right props can include some non-player characters as part of their entourage.
From the 2015 series:
Actor-Shared Background: Tina Shukshin is from Uzbekistan, just like her actress, Milana Vayntrub. In one episode, the power is cut off from the on-board universal translator and Tina reverts to speaking her native Russian.
Advertised Extra: The trailer for the show's premiere on DUST lists Dave Franco as a main cast member, but Franco only makes two uncredited appearances before his character is killed off.
Darkhorse Casting: When the series premiered, only three members of the main cast even had Wikipedia articles. Of the three, Trace Beaulieu and Joel Hodgson achieved prominence for their Mystery Science Theater 3000 roles, but were unknown to anyone who didn't watch the series, while Milana Vayntrub was recognized mainly for her appearances in AT&T commercials, which didn't use her name. Since the series ended, however, Karan Soni and Conor Leslie have further prominence for their respective roles as Dopinder in Deadpool and Donna Troy in Titans, while Eugene Cordero also gained more attention for how prolific he's been.