Rowley's mom is played by Robert Capron's real life mom Kaye Capron.

All of the children did their own singing in the audition scene on stage for the school play, except Greg Heffley.

While the studio was deciding where to film the movie, they said they were looking for the "perfect American town." Ironically, they found the perfect American town in Canada.

Before Zachary Gordon was cast as Greg Heffley, he was celebrating his eleventh birthday. His birthday wish was to get the part.

The character of Angie was not in the book. She was created exclusively for the movie.

In the scene where Greg and Rowley are in the cafeteria (and Greg describes it as a terrible place), there is lettering on the back wall which appears to spell out "SH**". Some of it is blocked by a pillar.

It took half an hour to film the scene where Colin hands Rowley the ice cream cone. This is because the cold ice cream kept melting in the hot gym.

When Greg and Rowley are outside building the snowman, they fix up the snowman to look like he was peeing in the snow.

Fregley's Halloween costume was a cross between a donkey and a unicorn.

In the Christmas scene where Greg throws a football at Rowley as he is riding down the hill, Zachary Gordon didn't actually throw the ball. He just pretended to throw it during filming and the ball was added later on as a visual effect.

Patty performs in a British accent while playing Dorothy in The Wizard of Oz play (Dorothy is an American character from Kansas).

The casting crew needed a young boy to play the role of Manny Heffley. Instead, they found two boys to be the perfect Manny.

As of February 2019, the Diary of a Wimpy Kid book series as a whole is the 12th-best selling book series in the world. The 11th-best selling is the Robert Langdon series by Dan Brown, the 10th-best selling is the San-Antonio series by Frédéric Dard, the 3rd-best selling is the Perry Mason series by Erle Stanley Gardner, the 2nd-best selling is the Goosebumps series by R.L. Stine, and the very best selling is the Harry Potter series by J.K. Rowling.

WILHELM SCREAM: When Greg and Rowley are playing the Twisted Wizard game, and when the orange dragon scorches the purple dragon to bones.

The coach's name in the book is Mr. Underwood, but in the movie, it's Coach Malone.

When the camera eases in on Chirag getting bullied by the two kids while Greg is introducing him, there is a teacher in the background who does not seem to be stopping the bullies. This is accurate to real life.

In the scene where they're having breakfast, Ice Age, another film owned by 20th Century Fox, is playing in the background.

During Greg's fantasy daydream, the actors who portrayed Greg and Quentin's adult versions were voiced by the actors who portrayed their young versions.

In the original books Patty wore glasses but in this movie and the later two films she does not wear them.

When Mr Winsky Gives Greg And Rowley The Safety Patrol Job He Says With Great Power Comes Great Responsibility Which Are The Words Of Wisdom By Uncle Ben In Spider-Man (2002)

Karan Brar's Acting Debut

Whenever this movie is shown on Cartoon Network, the part where Greg urinates on Rodrick was cut, and the bathroom scene was cut shorter

The scene where Frank drenches Greg and Rowley on Halloween was done in one take.

There was a scene in an earlier draft of the script where Greg runs downstairs in his underwear and then realizes that there are adults over at his house. A similar scene was in the sequel

When Greg is singing in the audition for The Wizard of Oz, L.J. Benet's voice is the actual the singing voice.