I mean, for instance, the one where they are on the alien hoverbike and fall through a roof or something and end up on a busy Marrakesh souk. As people quickly gather around to watch the MIB genius agents quickly deduce that this calls for immediate neuralizer (or whatever it's called) use. They zap the people who have gathered around to watch and..........then continue running through the Marrakesh souk and probably downtown Marrakesh as well without a care in the world on their alien hoverbike. Now, I'm no MIB agent, but what was the point of zapping those onlookers when you are going to run around the whole city with the bike anyways. You may as well ask why do they bother zapping anyone when they have zero problems using their alien technology in obviously visible places like the flying car in downtown Paris etc.

While I'm here, maybe it's just me, but that poster for the movie kind of makes me think it's a sequel to Blues Brothers 2000. Who know's maybe this would've worked better if they had gotten rid of the alien technology and given them saxophones intead and kept the movie as is otherwise. I can think of a name already:"Blues Brothers - Send in the clowns"