When Cage's character offers the money for his brother and the brother is in the car about to get crushed, the back window gets broken out twice.
13 Mustangs from 1967-1968 were modified to be "Eleanor" in the movie. One was a True Shelby GT500, but this was used by Bruckheimer as a reference piece and used by him personally. The rest were run of the mill Mustangs modified with bodykits and other goodies. One was chopped up to film certain sequences (in car shots, etc.), 2 were destroyed, and the other Mustangs were modified to perform certain tasks (Chases, Jumps, etc.).