There are endless challenges to getting an indie feature-length animated film made: Lack of money, not enough time, fruitless rewrites, a vision that can’t get across the finish line. When asked what the biggest challenge was while making their upcoming comedy “Mars,” co-writers and voice actors Sam Brown and Zach Cregger can’t help but riff an answer to a question that inelegantly ignores the elephant in the room.

“Well, Trevor died,” Brown says.

“Trevor died, that was a toughie,” Cregger says. “I guess it was getting it funded — that was bigger than Trevor dying. No, no, no, no, no. Also, Covid was annoying. So let’s go Covid, funding, Trevor dying.”

Trevor is Trevor Moore, the de facto leader of Whitest Kids U’Know, the five-person sketch group — consisting of Moore, Brown, Cregger, Timmy Williams and Darren Trumeter — behind “Mars.” The group, which began as a club at...