Continuity mistake: When he has the accident after hitting the dog, there is a big very noticeable dent in his truck. After he leaves the camp place it is gone and never seen again.
Continuity mistake: When John returns from the hospital, Maya is sitting down, then stands up. The camera then goes onto John, then back to Maya, then she stands up again.
Continuity mistake: When Dr. Dolittle was committed and talking to Blaine (and several other spots in the movie), he was very obviously wearing a very bad wig to try and look like braids. You can tell it's his own hair in the scenes where he is talking to the patients and/or his partner.
Continuity mistake: When Dolittle is a boy and his father sends the dog away, they show him crying, a single tear is coming down the right side of his face. The scene then shifts to the dog and back to young Dolittle. The single tear is now on the left side of his face.
Continuity mistake: When Dr. Dolittle is driving to the circus and talking to Lucky, sometimes he's wearing his seat belt, and sometimes he's not.
Continuity mistake: Dolittle passes by the trash can with the rats before operating the tiger. The garbage around the rats differs depending on the angle.
Continuity mistake: When the rats are sick for the first time, inside the trash can, a blue paper behind keeps appearing and disappearing between front and back shots.
Continuity mistake: When Dolittle operates the tiger, the blue cloth around his head differs in position and length depending on the angle.
Continuity mistake: In the scene when John is talking to the vet about Lucky, watch the vet's hand on Lucky's tail. It moves from the base in one shot to the middle in another. This happens several times. Also, the tail changes length and fur color.
Continuity mistake: When Lucky the dog is in Dolittle's car, he says "Tree, tree, tree" and in doing so, puts his paw on the button and gets his head stuck in the window. At this point you can see there is nothing next to Lucky's head, but in the very next shot he has placed his left paw on the window.
Continuity mistake: When the alligator is born, in close-up his head is up and standing out, but in full shot it is lying down. This keeps changing back and forth.
Continuity mistake: When the pigeon defecates on the doctor's face, the poo falls on the side of his mouth. Half a second later the mouth is clean and the poo is all over his chin, nowhere near where it fell before, so it couldn't have slid down there.
Continuity mistake: When Dolittle arrives at the woods, right before he parks, the side of his car is totally dusty and dirty. When he steps off, after a change of angles, it is spotless.
Continuity mistake: The crack on the alligator eggs keeps changing abruptly between shots, sometimes totally open, others almost closed without any logical order whatsoever.
Answer: Geno deliberately broke Mark's nose during the party after Mark made a snide remark. After the party, when Mark suggested a way to have John committed and still get their money, Geno had enough of Mark's ignorance and punched him in the nose again to add further insult to injury.