Matt is allowed to say the word "fuck" freely, while every time Jay says it, he's bleeped. When they switch bodies in The Book (2017), this is kept consistent and Matt is censored, while Jay is finally allowed to swear.
Season 2 contains more heavily scripted episodes, as during filming the main characters were being consistently recognized and pointed out which was ruining scenes.
The museum scene in The Band List (2018) caught the crew in serious enough legal trouble that the show was essentially in hiatus for two months as they tried defending themselves.
The pair of ripped jeans that Matt Johnson wears throughout the entire series is the exact same pair he's worn since the very first episode of the web series in 2006 and in The Dirties (2013), and keeps them for good luck. He says that they're so delicate at this point that he hasn't washed them since at least 2010 and that when doing more dangerous scenes, he collaborated with a costume designer to create a pair of "stunt pants" so he doesn't ruin the originals.
Originally a web series back in 2006.