Continuity mistake: At the bachelor party, Kevin Kline has a cigar in his mouth. In one shot, it's whole, the next it's frayed, then in the NEXT, it's whole again.
Other mistake: The day after the Academy Awards, there is tall corn in the fields and the kids are dressed for warm weather. The Academy Awards are in March, not a warm, corn-growing time in Indiana.
Continuity mistake: When Joan Cusack is sobbing in the road and throws herself on Matt Dillon's car, her lipstick and mascara are smeared, suddenly her makeup is perfect.
Deliberate mistake: When Howard walks up to the front of the church he is alone. Suddenly, when his bride comes out, the best man, maid of honor and flower girl are at the front of the church. This happens despite the fact that the music flows and there was not time for the others to enter.
Continuity mistake: After Kevin Kline leaves the church and is talking to Tom Selleck by the pond, the ducks behind him change positions and numbers from shot to shot.
Continuity mistake: When Peter is telling Howard about coming out (while sitting at the side of the road), Howard's hand is up near his face in all but one shot.
Continuity mistake: The cake Howard's mom has in the car is different from the cake at the reception when the ladies are talking.
Factual error: The movie opens with the Academy Awards, which as everyone knows are held no later than late March. Then Howard's wedding is no less than a week later, at which point he accidentally outs himself and is subsequently fired. It's clear that the kids' graduation is no more than a week or two later (made especially clear by the fact that Cameron, rushing to town, gets there the same night of the wedding and then is still there at graduation.) But high school graduations are in June or, at the earliest, May - which last time I checked was more than a week or two after the end of March.
Plot hole: Why would the press converge on Greenleaf to begin with. Nobody but the residents of the town know that Howard still thinks that he is straight. Why would press people from across the US think that there was a story there? Dozens of people get thanked every year at the Oscars and the press certainly doesn't do follow up stories on every single one of them.
Continuity mistake: When Kevin Kline goes to school the day after the awards show, the press chase him to one of the school doors. When the scene is shot from outside, the door opens into the building and he is pushing it open, but immediately after when the shot is from inside of the school and he is closing the door, it opens outwards and he is pulling it closed.
Suggested correction: When he goes into the school the Press follow him and he doesn't even close the outside school door. The door that they show him closing is the door to his classroom.
Continuity mistake: Right before Emily and Cameron dance in the street there is a shot of the front of the bar. The cars in front of the bar are different from the rest of the scene.
Continuity mistake: Joan Cusack is eating a bag of Utz brand snacks. Utz are not available in Indiana, but they are available in New Jersey, where the film was shot.
Continuity mistake: After Howard crashes on his bike and he is sitting down talking to Peter there is a big wet spot on his left knee in one shot that is gone in the next.
Continuity mistake: During the famous 'Be a man' dance scene the banana in the fruit bowl keeps changing positions between shots.
