Answer by taking a quote from the following article:

The Simpsons Movie is a 2007 American animated comedy film based on the Fox television series The Simpsons. The film was directed by David Silverman, and stars the regular television cast of Dan Castellaneta, Julie Kavner, Nancy Cartwright, Yeardley Smith, Hank Azaria, Harry Shearer, Tress MacNeille, Pamela Hayden, Maggie Roswell and Russi Taylor, with Tom Hanks, Green Day and Albert Brooks in guest roles. The film follows Homer Simpson, whose irresponsibility gets the best of him when he pollutes the lake in Springfield after the town has cleaned it up following receipt of a warning from the Environmental Protection Agency. As the townspeople exile him and eventually his family abandons him, Homer works to redeem his folly by stopping Russ Cargill, the head of the EPA, when he intends to destroy Springfield.

20th Century Fox announced on April 1, 2006 that the film would be released worldwide on July 27, 2007. The film was released a day earlier in Australia and the United Kingdom. Little information about the plot was released in the weeks building up to the film's release. Groening did not feel that "people look in the TV section of the newspaper and think, 'I'll watch this week's Simpsons because I like the plot.' You just tune in and see what happens."  Fox held a competition among 16 Springfields across the United States to host the American premiere. Each Springfield produced a film, explaining why their town should host the premiere, with the results being decided via a vote on the USA Today website. Springfield, Minnesota dropped out on May 31, 2007. The winner was announced on July 10 to be Springfield, Vermont. The town beat Springfield, Illinois by 15,367 votes to 14,634. Each of the other 14 entrants held their own smaller screenings of the film on July 26. Springfield, Vermont hosted the world premiere of the film on July 21 with a yellow carpet instead of the traditional red.  The film was rated PG-13 by the Motion Picture Association of America for "irreverent humor throughout". The production staff had expected this rating. However, the British Board of Film Classification passed the film as a PG with no cuts made. A BBFC spokeswoman said regarding Bart's brief nude scene, "natural nudity with no sexual content is acceptable in PG films".

what was it with the cuts?
The film was rated PG-13 by the Motion Picture Association of America