To further explore the character of Donovan Drake, Jason Bee started a YouTube channel called "Donovan Drake's: My Blank Slate," where he would vlog as Donovan about his life events months before the film takes place. There were 26 episodes and the final post is the teaser to the film.
There are many references to superheroes in the film. Some of the more obvious references lie in the voiceover dialogue Donovan has with himself. A less obvious example would be in the scene where Donovan tries to tell Haley about his condition, but chickens out. This is a shot-for-shot nod to Batman (1989) where Bruce Wayne tries to tell Vicky Vale he's Batman.
In the scene where Donovan tries to tell Haley about his condition, the song playing in the background is called "Superman" by Ghost Ovell. The song is the personification of "Mania," as it relates to bipolar disorder, taunting someone currently afflicted by a depression while offering them false hope.
The "hair" bit at Heather's house (Donovan's ex-wife) was ad-libbed.
It was Damon Carney's idea for Steve to continuously call Donovan a different insulting nickname every time they see each other.