The 80 foot long "Worm Tube" becomes so tight at its end that sometimes firefighter's can't get through. During the movie's filming one recruit got stuck and needed rescue, via a rope tied to his legs.
Several scenes were filmed in extreme fire conditions where room temperatures exceeded 800 degrees Fahrenheit. A special box was constructed to protect the cameras. Even then the cameras had to be removed every few minutes to allow to cool. One camera suffered damage and had to be repaired.
In one particular scene, shot in the fire building, Captain Lynch's voice is breaking up. This is a result of his wireless microphone melting.