The interiors of the VFW post were shot on location at a real VFW hall in Grand Prairie, Texas (specifically Post #2494). Several of the hall's real veterans appear as extras in the bar during the opening scenes.
At 01:08:12, Boz (Travis Hammer) says "Fire it up". This was a chant by T-Bird (David Patrick Kelly) and his crew in The Crow (1994).
All the gore f/x were done practically.
On the list of features seen above the cinema, one of them is called Bliss (2019), a reference to Begos' previous film.
VFW stands for Veterans of Foreign Wars. An organization of U.S. war veterans, who, as military service members fought in wars, campaigns, and expeditions on foreign land, waters, or airspace. The purpose of the VFW is to speed rehabilitation of the nation's disabled and needy veterans, assist veterans' widows and orphans and the dependents of needy or disabled veterans, and promote Americanism by means of education in patriotism and by constructive service to local communities.