Clara's living room and kitchen, Tinkerballa's bedroom, Vork's shed, and Bladezz' garage are all sets based in Felicia Day's real house to cut down costs on production. Venom's bedroom in season 3 was actually the flip-side of the room from which Tinkerballa gamed.
The actor who plays Bladezz (Vincent Caso) and the actress who plays his little sister, Dena (Tara Caso), are real-life brother and sister.
Several of the outdoor scenes were shot in residential areas without permission, causing Felicia Day to be constantly on edge while filming.
The frequent references to Codex's anxiety issues stem from Felicia Day's real-life struggle with anxiety. As a coping mechanism, she often writes dialogue for Codex which refers to her own anxiety and fears.
The game that The Guild play is literally called 'The Game', and is even shown illustrated in several signs and on video game boxes in the backgrounds of various seasons. This was to avoid any copyright issues and make the game more general.