The metal sheets used to cover the windows fell off of one of the windows almost hitting actress Tiffany Jhingoor in the head. She jumped out of the way just seconds before it crashed to the ground.
The furnace was only a few feet away from actor Joe Criscitello and would occasionally click on since it was 20 degrees out while filming. Luckily there was a switch that one of the crew used to turn the furnace off periodically while filming, much to the dismay of the tenants upstairs in the building.
The scene where Man in Black (Adam Holley) is punched and spits up blood was never in the original script and was added in by the director during filming.