“Dark Knight Rises” enthusiasts, start your engines. Three camouflaged Batmobile Tumblers drove through the streets of Pittsburgh over the weekend, where “The Dark Knight Rises” is filming. In case you are a non-nerd, the “Tumbler” is a military vehicle modified for the Caped Crusader by Lucius Fox (Morgan Freeman) in 2005’s “Batman Begins.” Production for Christopher Noaln’s third Batman film kicked off last week in the city.