According to Martin Lawrence, Will Smith and he had to rewatch "Bad Boys" 1 and 2 multiple times everyday in order to get their characters back on track, since it's been so long after the second sequel.
The contact photo Mike has for Marcus on his cell phone is taken from the Bad Boys II (2003) poster.
Directors Bilall Fallah and Adil El Arbi made their Hollywood debut with this movie on the strength of their Belgian films Black (2015) and Gangsta (2018). They stated in interviews that this came with some pressure, since their agents had made it very clear to them that if the movie wasn't successful, it would most likely be the end of their Hollywood career. However, they loved making the film and cherished the opportunity to work with their idols Will Smith and Martin Lawrence.
On October 31st 2018, Martin Lawrence tweeted a picture of himself and Will Smith on the set of Bad Boys III (Bad Boys for Life) with the caption "Bad Boys for life", confirming once and for all that production is finally underway after years of delays.
Despite both actors receiving top billing, this is the first film in the series where Will Smith is billed first & Martin Lawrence is billed second.
Jasmin Lawrence: Martin Lawrence's daughter is one of the two girls that don't let Marcus and Mike into a club.
Michael Bay: the director of Bad Boys (1995) and Bad Boys II (2003) appears as the wedding master of ceremonies who announces Mike Lowrey's speech. Bay directed the scene himself, which is filmed with his signature 360 degree shot.
Bilall Fallah, Adil El Arbi: Fallah is the guy trying to seduce Rita in the club. El Arbi gets pulled out of the Jeep by Mike while getting out of the club. The latter is a direct reference to a similar director cameo by Michael Bay in Bad Boys (1995), but Bay's character got to keep his car.
Bilall Fallah, Adil El Arbi: [Antwerp] The nightclub the birthday party takes place in is called Zillion. It's the same name as an iconic discotheque which operated 1997-2002 in Antwerp, Belgium, the directors' hometown.