 SPOILER: In the scene where Dom is attacked by the killer in the  stairway at the abandoned building, it was required for the killer  to drop the knife after stabbing Dom once, and have it land directly  on the handrail below, sticking straight up. Director Alfred Sole  only had one knife, and had to drop it repeatedly, then have a crew  member run back down the stairs to retrieve it, and try it all over  again. Finally, after twenty