There are a number of things on my list of "things that writers get wrong about firefighting," but oddly enough I didn't include fire sprinklers.
We've all seen movies and TV shows where someone, often a bad guy, sets off a fire sprinkler system in a building in order to get people to leave the building, distract them from what's really going on, or for some other nefarious reason. All too often, one activated sprinkler is depicted as setting off the whole system, creating an indoor water park of sorts.
Reality: For most (if not all - I'm not up on current systems and codes!) residential and commercial fire sprinkler systems, only the affected sprinkler head(s) will activate.
Check out this video from the Home Fire Sprinkler Coalition (HFSC) to see how sprinklers work.
Obligatory PSA: If you want to learn more about the life-saving benefits of home fire sprinklers, go to http://HomeFireSprinkler.org.
While you're doing that, I will be adding fire sprinkler systems to my myths of fictional firefighting.