Paul Braunstein who plays Ron makes fun of The Saw movies early on. He actually played Ryan in Jigsaw 2017
When the judge is recounting the events of his abduction, he mentions seeing only one grocery item -oranges, rolling on the ground. Oranges rolling on the ground is a cinematic reference to impending peril, best known by the movie The Godfather, when Don Corleone was shot on the street.
The source code shown at various points in the movie are all actually part of the Linux kernel source code, specifically groups.c.
During the discussion between Lieutenant Roy and Detective Steptoe, when the camera switches to Roy, the Clan MacPherson coat of arms can be seen to the upper right. The motto is Touch Not the Cat Bot the Glove, and refers to the clan's reputation as not to be trifled with. In keeping with the story line of poor policing convicting the wrong man for the crime, it foreshadows what may come.
When talking about famous unsolved crimes, Henry mentions to the judge the assassination of president Kennedy. Donald Sutherland previously appeared in JFK - Un caso ancora aperto (1991), which covers the case.