Factual error: In some scenes at the climatic fire-fight, you can see that barrels have stickers indicating what's in them. Talking to a Haz-Mat Firefighter, in at least 3 scenes, the labels clearly indicate something that would've fried our heroes in that extreme situation. One barrel that he saw would've exploded because the chemicals label (that he could see; he could be wrong) react to ordinary heat!! Also, since this was a chemical fire, there would've been procedures to "decontaminate" firefighters instead of simply stuffing them into an Ambulance. It's possible that some industrial chemicals could pose a serious risk far worse than any Biological Agent if spread.
Factual error: When Bull goes charging into any of the fires in the film, he never buttons his protective coat. Any firefighter that did that would suffer severe burns. Also, he doesn't wear an SCBA, he would have suffered smoke inhalation without one.