In the end scene when Darryl and Calvin are walking back into the house Darryl tells Calvin to be quiet so his wife won't hear, but she isn't home yet from going to get her father out of the mental hospital.
When Calvin and Percy narrowly escape the police in the drug store, they hop into a cab, which is a Buick Century. When they get to Darrel and Vanessa's house, the cab is a Ford Crown Victoria. You can tell by the back window.
When Darryl is looking at the video Pops made with the teddy bear, the angle of the camera/bear would make it seem like it was at shoulder height or higher. When Darryl finds the bear, it is on a chair. That would have given the video a much lower angle.
When Walken and his men go to the house to recover the diamond, he orders one of them to take the baby upstairs. He then puts the baby in the cot and turns the light off. Calvin then starts to hit the goon across the back of the head multiple times. When the goon turns to look at the baby the second time, he has bruises on his forehead.
When Calvin is being examined, the doctor notes that the scar on his abdomen could be from an appendectomy. However, the scar is on Calvin's left side. Any doctor would know that the appendix is on the right side.
On the cover of the DVD, Calvin's tattoo is on his forearm and says "United States Marine Corps". In the movie, the tattoo is on his upper arm and says "82nd Airbourne". On the back of the DVD there is no tattoo on the same forearm.