When "Frankenstein" vomits on the floor, it is partially on the floor and partially on the carpet. Later, it is totally on the floor with none on the carpet
The skater that trips on the stick is shown skating past the kid before he throws down the stick.
At the super market, Julian has an itch and Corinne lays a package of frozen vegetables on his arm. In the first shot, the package is right side up. But in the very next shot the package is upside down.
When Sonny is pouring milk into the lotion bottle for Julian to put it on his cereal, the bowl is heaping with cereal but in the next shot, it is level.
When Sonny does the wrestling move on Nazo, and he passes out, Nazo's head is first turned to the left. In the next shot, it is turned to the right. Then turned to the left again.
When Sonny decides to adopt Julian, his friends Tommy and Phil try to discourage him by warning him of the big responsibilities of parenthood.
However, as lawyers, they never remind him that he would need Kevin's legal permission to do so.
When Sonny is teaching Julian how to do Chief Jay Strongbow's sleeper hold, he does it head-and-arm. Strongbow's sleeper was never in the head-and-arm fashion.
Urinating in public especially on buildings is illegal especially in New York yet Sonny and Julian never got in trouble for urinating on buildings.
Courtrooms do not allow food or other drinks (water only). Yet Sonny gives the unnamed homeless man a McDonald's bag in court and the homeless man is seen eating a few minutes later.
When the homeless man is eating his McDonald's breakfast in court, he takes bites of a cantaloupe. McDonald's does not sell fruit on their menu.
When the skater coming down the path in the park hits Sonny's stick, he careens down the hill into the pond between two large rocks. The smaller rock on the right lifts and floats a little to the right.
When Julian spills the milk on the floor the milk is spreading towards the back of the room. Then when the camera switches back to Sonny the milk is a circular pool before Sunny put the newspaper on it. The newspaper never gets wet.
When Sonny is on the payphone, Julian is show mouthing something to the guy on the payphone behind Sonny. The guy is giving him instructions.
During the court hearing about getting custody of Julian. The judge asks for the first witness and the first witness on the stand was Mr. Herlihy (the drunk old man from the bar at the beginning) but Corinne or The Delivery Guy were the first ones to witness Sonny with Julian.
Columbus Day in 1999 was on October 11th not October 14th also October 14th in 1999 fell on a Thursday not a Monday.
The game Julian is playing is Twisted Metal III (1998). However, the sounds we hear while he's playing are generic "boop-boop-beep" arcade noises, and not actual sounds from Twisted Metal III.
During the Kangaroo Song, the lyrics on the TV show "hop hop hop all DAY", but the singer actually says "hop hop hop all Night".
At the end of the trial, Corinne's shocked reaction upon learning that Julian belongs to her fiancé (Jon Stewart/Kevin Gerrity) makes no sense. Throughout the trial, the judge makes reference to Julian as "Julian McGrath, also known as Julian Gerrity" and several statements were made regarding "Sonny Koufax impersonating Kevin Gerrity" so there is no way that Corinne wouldn't have put the pieces together to realize what the situation was.
When Julian won't stop talking to the homeless man before going into McDonalds, the homeless man asks Sonny to get him a Sausage McMuffin. When Sonny and Julian come out from McDonalds the homeless man asks Sonny where his Egg McMuffin is.
At the end of the movie when Sonny says "Vanessa?" while holding Julian (at around 1 hour 30 mins), Julian simultaneously mouths the line.