Continuity mistake: When Marcus Burnett drops Julie Mott off at Mike Lowery's apartment it's dark outside. When he leaves shortly after, there is daylight outside.
Audio problem: When Mike and Marcus are driving in Marcus's car, just before they sing Bad Boys, in the shot over Mike's shoulder we see that what he is saying does not match the movement of his mouth. (00:22:40)
Suggested correction: But Will Smith is not speaking in that shot. Martin Lawrence is saying something corny ("I'm a baaad boy") that is the cue for the song. Smith is just mouthing under his breath.
Other mistake: In the film, Lawrence and Smith's characters are Narcotics detectives with Miami Dade Police. There's no way they should be at any homicide investigations. Narc and homicide are totally two different units within law enforcement, so it's unlikely narcotics units would be at a homicide scene. Being the scene where they're investigating Smith's friend getting killed, and then they stumble across the dead body at the mansion.
Suggested correction: The captain called Mike and Marcus to the scene to help because it appeared related to the missing drugs. They were there to find leads to the missing heroin.
Yes, that could be correct, but the chances of that happening are slim to none. A captain from Narcotics wouldn't even have authorization to call his detectives to a murder scene to help out homicide detectives working a murder. Any information or clues would be collected and shared with other units or agencies if deemed appropriate.
Other mistake: Near the end of the movie, Martin Lawrence and Will Smith are in a Porsche catching the bad guy. The whole time Martin Lawrence is driving, BOTH hands are on the steering wheel. Now most of us know that Porsches have a manual transmission, so shouldn't Martin Lawrence be switching gears during the chase?
Suggested correction: Hopefully someone else can confirm, but it appears that from around 1995 onwards some Porsche models came with an optional 'tiptronic' automatic transmission.
It was Michael Bay's own personal car used in the movie, a manual transmission model. But even if we do not use "outside" knowledge, we see the gear stick in the movie at the very beginning when Martin Lawrence spills fries all over it. So no, despite what the correction says, it's not an automatic version.
Other mistake: In the scene where Mike returns to his apartment for the first time since Julie was living there, as they walk towards the elevator Chet says "Hey Mr Lowrey" to Mike then says "Hey Mr Lowrey" to Marcus although Marcus never told him that he was taking Mike's identity. (00:59:45)
Suggested correction: It's not in real time. They could have been back on a different occasion; we just aren't shown it.