Visible crew/equipment: Soon after Dennis dies via the Hobgoblin induced fantasy, Mr. McCreedy comes to check on him; when he gets to the door where they stopped earlier (where McCreedy told him not to proceed further down the hall), the actors' marks, T-marks in black duct tape, are visible on he floor where they stopped earlier.
Hobgoblins (1988)
1 visible crew/equipment mistake - chronological order
Directed by: Rick Sloane
Starring: Kelley Palmer, Paige Sullivan, Steven Boggs, Tom Bartlett
Revealing mistake: None of the grenades Nick throws at the bar does any damage.
McCreedy: The vault... I tried to warn you... those creatures... the vault... I tried... All my work! Thirty years, I have tried to prevent this from happening.