T.J. Miller reportedly did not get along well with director Michael Bay during the course of filming. Miller compared it to a "very bipolar experience" working with Bay, who once told Miller on set, "Nothing that you've said is funny, T.J.! Not one thing all day! We hired you to be funny! There's three hundred people here! None of them are laughing at you! Say something funny! I can still cut you out of the movie!"
Michael Bay had resisted including the Dinobots in previous installments, as the writers had not come up with a convincing in-story reason for why giant robots, who (according to the first few installments) seek to maintain a low profile by disguising as everyday vehicles and appliances, would take the metallic form of giant reptiles who went extinct eons ago.
(at around 2h 10 mins) For the first time, Optimus Prime speaks in his native Cybertronian.
Originally, Michael Bay was not going to direct a fourth Transformers movie, but he had an experience that changed his mind. After Transformers: Dark of the Moon (2011), Bay finally got to visit the Transformers ride at Universal Studios. Upon seeing fans waiting three blocks for the attraction, he realized he was not ready to leave the franchise just yet.
Calvin Wimmer: (at around 12 mins) an editor who worked on all the Transformers films, appears in this film as a realtor client. Wimmer had also previously voiced the Wheelbot in Transformers: Revenge of the Fallen (2009).
Michael Bay: (at around 1h 18 mins) the passenger of the truck that Bumblebee and Optimus destroy after they jump over bridge during Galvatron's attack.