Ok there has been a lot of questions as to why the truck Ironhide was in Chicago, he was already dead at that point, la la la Here is why: 1) They never film movie scenes in order 2) The Department of health and human services building takes place in Washington DC in the movie, but it is actually the post office in Chicago, redecorated. There were some scenes filmed with Ironhide driving in an out of the post office/department of health and human services plus some outside scenes as well. So I hope that solves the mystery as to why the GMC Topkick was in Chicago. 3) They then placed Ironhide around to please the ever growing crowds and allow them to take pictures with Ironhide etc. There are some people on these boards that have such pictures. and yes I know that I didn't have to put spoilers in the thread title but I decided to do it as a nice courtesty
The scene with Ironhide, Sideswipe and the Dreads was also shot in Chicago, over by McCormick Place. Plus, you never know when Bay might need to just shoot footage of Ironhide driving around.
I knew I recognized McCormick place. They just shot that scene in Chicago - and said it was just Washington D.C.