At Club Scum, Nick addresses Sergeant Parker as "sir" and salutes him. In the U.S. Army, sergeants are not addressed or saluted by junior soldiers in this manner. Theose courtesies are reserved for commissioned officers.
Nick stops by while the hobgoblins attack Daphne, Amy, and Kyle in the living room. When he stands outside, watching through the window, the front door is shut. In the next shot, he runs up to an open front door.
Nick throws the grenades from a crouched position in front of the empty bar, which is in disarray. When they land beside the bar, patrons are drinking at the bar. The terrified patrons leave the bar after Roadrash throws Kevin and Kyle back into the club. The patrons vacate the same bar seconds later, when Kevin, Kyle, and Daphne hide under the table.
Soon after Dennis dies, Mr. McCreedy goes to check on him. When he gets to the door where they stopped earlier (when McCreedy told him not to go further down the hall), black duct tape T-marks are clearly visible on the floor.
The vault that contained the hobgoblins for 30 years is apparently only one flight of stairs up from the ground floor. When Mr. McCreedy blows up the vault, the explosion only affects the top floor of the building.