The robots aren't the only part of the latest "Transformers" film that changed. Led by star Mark Wahlberg, a whole new cast was brought in to give a fresh start to the blockbuster franchise.
"Transformers: Age of Extinction" stars Wahlberg as a mechanic who strikes up a friendship with good-guy robot Optimus Prime.
Wahlberg said the idea of joining the franchise came while he and Bay were working on last year's film, "Pain and Gains."
"I've never done a sequel to any of the movies that I've done and this is my first installment in the series. So, still not really a sequel for me. Just thought it was fun to do something different and I really wanted to work with Michael."
The first three films were anchored by Shia LaBeouf, and Wahlberg has previously said he felt pressure about stepping into the shoes of other actors. Still he jumped at the opportunity, and while he's signed to do future installments, "I'm not doing it if Michael doesn't do it. So we'll see what happens."
At the film's worldwide premiere in Hong Kong, Bay praised the 43-year-old Wahlberg as a leading man with maturity and gravitas.
As a father of four, Wahlberg saw his scenes with on-screen daughter Nicola Peltz as a sign of things to come and says he's fiercely protective of his own two daughters. "I'm not excited about that part of it," he admitted of their becoming teenagers.
The 19-year-old Peltz said she took Wahlberg's advice to come to the film set extra prepared.
"He told me, 'Before you go to set, know your script, know your lines, know everything about the script.'"
Another new addition, Kelsey Grammer, said he didn't mind playing a villain since he got the chance to work with Bay. "It's like throwing a lot of things up in the air (at) one time, and somehow he pulls them back down, and sticks them in his movie. He's got so many ideas all the time. His mind is so quick and rich, and creative. It's kind of like a wild ride just to work with him."
Hong Kong and China play an important backdrop in the latest installment, another indication of China's growing importance to Hollywood. The franchise's third film, "Transformers: Dark of the Moon," earned $1.1 billion at the global box office, with $165 million from China, its second biggest market after North America.
But it hasn't been smooth. A Beijing property developer wants the film to be edited and for Chinese screenings to be suspended because it says the film's production partners failed to fulfill sponsorship obligations. The Beijing Pangu Investment Co. Ltd. owns the dragon-shaped Pangu Plaza featured in the film.
Production in Hong Kong also was briefly disturbed by two extortion attempts on the set last year. In one case, a man reportedly tried to throw an air conditioning over Bay's head. One assailant was later sentenced to 30 months in prison.
At a news conference, Bay said he thought the sentence was harsh. He also said that after the incident, people came up to him and apologized to him on behalf of Hong Kong.
Supporting actor Jack Reynor said despite the incident, the cast and crew had a great time on set. "Our experiences of Hong Kong were all very positive ones."