Bat-Mite is a fictional character appearing in American comic books published by DC Comics. Bat-Mite is an imp similar to the Superman villain Mister Mxyzptlk. First appeared in Detective Comics #267 (May 1959).
Vigilante and Peacemaker's target practice with Peacemaker was inspired by James Gunn's childhood in Missouri, when he and his friends used explosives to blow up things.
A police car has "Charlton County" on it. Peacemaker was originally a Charlton Comics character, before the company was bought out by DC.
In the comics, William Heller was White Dragon and first appeared in Suicide Squad #4 (August 1987). He was discredited by the Suicide Squad and later recruited as a member, when he was wearing a suit of battle armor he had used against the JSA. He betrayed the team and was killed by Plastique.
The man tied up wears a shirt with the same character that Rick Flag has on his shirt in The Suicide Squad (2021).