“Hong Kong is a very visual city,” he said in an exclusive interview with the .

Saying it was a city he had always wanted to film, he recalled a memorable visit, just after completing filming of , the 1998 release starring Sean Connery and Nicholas Cage, when action superstar Jackie Chan was his host.

“I literally called Jackie Chan in Los Angeles,” Bay said. “He invited me to dinner. He had very bad English: ‘I don’t watch your movies. I studied your movies’. He was so nice. He took me out for two nights.” But he wasn’t impressed by the shark’s fin soup Chan treated him to.

On this visit, things started to get interesting on his first day when he was attacked by a man wielding an air-conditioning unit who allegedly tried to extort HK$100,000 from the crew.

But was the mechanical assailant really an air conditioner or a Decepticon, one of the evil Transformers who have waged war for eons against the Autobots?

”It could’ve been,” Bay joked. “That’s why I was unguarded.”

He ducked under the air-conditioner and the security guard brought down the attacker.

“It was kind of scary. The Hong Kong crew was embarrassed. They even considered paying him five times more but I said no,” said Bay.

After that incident he wrote on his Facebook page saying that the guy tried to bite like a zombie from World War Z.

“It was a true story. But after that it was great.”

The crew then ran into strangers allegedly trying to extort money from them when filming in To Kwa Wan. That didn’t offend Bay. Instead he was overwhelmed by Hong Kong people’s concern over the incidents.

“In the restaurants, in the hotel, I must have 30 people coming to me saying ‘I’m so sorry’. But it was such a silly incident,” Bay said. He was also surprised how the incidents got looped into international news reported on BBC and CNN.

Producer Loreanzo di Bonaventura was also touched by people’s concern. “They are very concerned about our feelings. We met 1,000 people and there were three idiots,” he said.

Video: Michael Bay on the air con-wielding triad member: "I grabbed him by the neck".

Filming the fourth Transformers instalment was a big operation involving at least 100 local crew. Bay said a lot of the equipment and at least 10 cars had to be shipped to Hong Kong – including some massive vehicles that were disassembled into smaller parts to fit in an air cargo hold.

Bay said it took him nine months – with a lot of help from the government – to work out the Hong Kong shooting plan. And despite having made three Transformers movies and many big-budget action blockbusters such as and , it was still a challenge.

“Hong Kong was very hard,” said Bay. “I’ve had difficult locations in my life. But shooting in the market with so many people watching ... it made it very challenging.”

Bay managed to get 30 to 35 minutes of what will be a two hour blockbuster - including a Hong Kong set in Detroit that he blew up: “There was a lot of dynamite.”

Beyond that, Bay was careful about not revealing too much about what role Hong Kong would play in the film or why Autobots like Bumble Bee had to come here.

Video: Director Michael Bay on how Transformers saved the beloved Camaro from extinction

Asked if any elements had been changed or adjusted - as in other blockbusters such as the latest instalment - to appease regulators of the China film market, now the world’s number two, Bay replied with a definite “no”. Filming in Hong Kong had nothing to do with it either, he said.

“I can still shoot in Texas and people in China are still going to see it,” he said. “You want to do something new and different. I’m tired of shooting in Los Angeles ... I almost shot it out. You need new inspiration. This is the city that I always wanted to shoot.”

The fourth Transformers instalment is the latest in an array of Hollywood blockbusters filmed on location in Hong Kong, after the (2008), (2011) and . Michael Mann finished filming here couple of months ago.

Asked if he might follow the footsteps of his friend Nicholas Cage who earlier said he might want to make Hong Kong his second home, Bay thought it might be an interesting idea. “I want to do some business in China and this part of the world,” said Bay, but that might not be a movie yet. He said he got a call from Dalian Wanda group, which acquired the US cinema operator AMC Theatres last year, but he was out of town.

“Maybe designing a car,” said Bay, adding that he might want to develop lavish online video games.

Bay had high regard for Hong Kong people – “very genuine, very polite”.

He said the scripts were sent to China’s censor body SARFT and the previous Transformers sailed through without any problems. He said with this film, he followed the protocol from the government of what would happen if something happened.

But he still declined to reveal the plot, he only said: “We are not destroying Hong Kong.” He said the story started in the US and there was a reason to go to China. Is Hong Kong a great hiding place for the Decepticons? “I can’t tell you how they get here.” Are Autobots rescuing Hong Kong from something? “They are not rescuing Hong Kong but definitely rescuing something.”

Hong Kong came into the picture when the scouting began, one to two months into the writing. He was in Hong Kong for three days and took thousands of pictures.

A number of Hong Kong and mainland actors, including Li Bingbing, Ray Lui Leung-wai and Michael Wong were seen on the Transformers set. Bay said he was glad that they were on board, albeit playing relatively smaller parts. “Some did it because their kids are fans of Transformers,” said Bay.

Bay and his crew leave Hong Kong today to continue filming at Wulong in Chongqing and on the Great Wall in Beijing.