Doing It for the Art: Bay managed to get the entire city of Chicago to help them with filming the entire climax. Shia LaBeouf and the other cast members were in awe of how much access they had to the whole of the city on a daily basis. Plus the entire wingsuit sequence was put in after Bay saw a TV special on them, and they are actually flying between the skyscrapers wearing portable 3-D camera helmets.
No Export for You: Hasbro cancelled the American release of the sixth wave of DOTM toys, including the much-anticipated Human Alliance Soundwave, due to low retailer demand. The cancelling of the line also means a Dino/Mirage toy is probably never coming.
Product Placement: The Wreckers take the appearance of weaponized NASCAR Sprint Cup Series as their car modes (armorized versions of the #42, #48 and #88 cars of Juan Pablo Montoya, Jimmie Johnson and Dale Earnhardt, Jr.). The Wreckers themselves also circled the track during the pace laps of the 2011 Daytona 500, at which Michael Bay and Josh Duhamel were the grand marshals who gave the starting command.
The Twins from ROTF were scripted into the movie but were carefully removed from the final cut (you can briefly see their vehicle modes in a line-up shot). Their roles would have been to be killed by Sentinel Prime after he reveals himself as a traitor by killing Ironhide. Maybe they weren't confident in getting an Alas, Poor Scrappy reaction....