Directed by: Barry Sonnenfeld
Starring: Tommy Lee Jones, Will Smith, Vincent D'Onofrio, Rip Torn, Tony Shalhoub, Linda Fiorentino
Continuity mistake: The Bug pulls his new "Edgar Suit" skin back tight over his face and the wife faints. In the wide shot, he is still holding it back, but the head is completely normal. (00:15:30)
Continuity mistake: Before Kay erases the memories of the border patrol cops, he holds the neuralizer with his left hand while adjusting its knobs with his right hand. In the next shot, he's holding the neuralizer with his right hand.
Revealing mistake: When Will Smith throws a rock at the escaping Edgar alien, if you watch the rock after it hits the alien, it disappears after hitting the ground. (01:23:20)
Large cop: If you were half the man I am... [Jay looks pointedly at policeman's stomach] I am half the man you are!
Trivia: After reading the script with his wife, Barry Sonnenfeld (the director) turned to his wife and said "Tommy Lee Jones". She turned to him and said "Will Smith", and that is how they were cast. This is confirmed by Barry Sonnenfeld on the DVD commentary.
Answer: K and his partner both knew about aliens living on Earth, and made it their duty to make sure no one else knew about it. When the trooper saw Mikey in his real form, and Mikey spotted him, he attacked the trooper in an attempt to kill him, probably to ensure that the trooper wouldn't be alive to expose them. Since K and the other agent were already aware of Mikey, as they had dealings with him before, Mikey didn't attack them.