Factual error: The device used near the end of the movie for ferrying people to another building is repeatedly referred to as a "breeches buoy." It is actually a bosun's chair. A breeches buoy was an earlier, more primitive device that was basically an oversized life preserver with a pair of large canvas trousers (breeches) sewn to it.
Factual error: When the fire department first arrived, they should have had the utility provider shut off the gas lines to avoid just the type of explosions that happened continually throughout the movie.
Answer: Where the stairs were blown out they could have crossed over to the adjacent stairwell and back.