In the animal shelter sometimes the bird is on Rianna's finger then it is on her shoulder then it is on it's perch then back on her finger.
The roof of Marvin's car was flattened by the boulder. After the surgery, the roof was only half flattened.
Sergeant Sisk's cigar disappears from his hand when he is in the bar imitating Marvin.
When the car stops rolling the first time, there is a tree behind it. Later, when the car has rolled over the edge, the tree is gone.
When Marvin is fighting with the chimp in the animal shelter while visiting with Rianna he twists the chimps nipple. In subsequent shots, his hand is alternately on/off the chimp.
When Sergeant Sisk, played by John C McGinley, enters the Mayor's party in full dress uniform, he is wearing police ribbons & awards of the Los Angeles City Police Department along with US Military ribbons and awards. The first ribbon below his name tag and to the left is the Police Meritorious Service Medal, the second medal is the Police Star, the first green, yellow and red ribbon in the second row is the Police Distinguished Service Medal followed by an unknown ribbon and another unknown ribbon. The third row left is the US Marine Corps Pack Leader ribbon, the middle one is unidentifiable, with the third one being the the US Army Service ribbon. The police medals should be in this order: the Police Distinguished Service Medal, the Police Meritorious Service Medal followed by the Police Meritorious Unit Citation followed by the Police Star. The order presented in error is: two, four, one, three.
When Marvin talks to Rianna about the date, he says he will pick her up at eight. But later on he is waiting at the bar for her when she arrives.
There is no way Marvin would be able to survive the car accident in the mountains.