Goofs

When they are washing the car, Greg first makes a small circle, next shot the circle is double the size, next shot the circle is gone, next shot it reappear.

At the retirement home when Greg is talking with Holly, an elderly man in yellow passes in front of them. In the nest shot he appears behind them.

During the store scene, the boys are scene taking multiple bites of the hot dogs, but in the next shot the hot dogs are completely whole.

When Rodrick places fake vomit on Coach Malone's car, Coach Malone drops his chips and his pop cans, and his legs are wide open. In the close-up of the spilled food, Coach's legs are together.

At the talent show, after Greg and Rowley's performance. Holly goes backstage to talk with Greg, immediately after that shot it shows Loded Diper playing and it show a shot of the audiences; Holly is back at her seat in a matter of seconds.

On YouTube, Greg and Rowley uploaded a video of him sitting on Manny's "present," and later they discover it has just four views. However it has over 20,000 comments (24,963 to be exact) and with just four views that would mean 6,241 comments per viewer.

When Greg and Rodrick is being chased by Coach Malone, they enter the mall that is called the "Planview Mall". The actual mall is called "Park Royal" in Vancouver, Canada (which is where the Diary of a Wimpy Kid movies are filmed) and in the shot where Greg and Rodrick enters the mall, they walk over the welcome mat on the floor with the Park Royal logo.

When Rodrick gives Greg and Rowley a ride home from school in the van they roll around in the back, football pads can be seen sticking out of Greg's (stunt doubles) pants when he rolls on his stomach.

When Rowley and Greg are at their lockers talking about the party, Rowley speaks but his lips don't move.

During the roller rink scene, when Couples Skate begins, "Always" by Atlantic Starr starts playing. However, when it cuts to a shot from behind Bill, who is the DJ, look carefully at the only turntable with a record on it. The record is blank and clearly not spinning.

When Frank Heffley is trying to rub the chocolate stain off Greg's pants, a crew member can be seen in the car window's reflection holding a camera.

When Rodrick prints the "100 Years Ago" essay for Greg, there shouldn't be a grade on it because it's from a saved document from the computer. Therefore, Mr. Huff shouldn't have been able to find out that Greg did not write his own paper.

In the previous movie, Greg gives Rowley the Cheese Touch, and it's passed on to Patty when she hugs Rowley. In this movie, Greg and Rowley claim Greg passed on the Touch to the new kid in school.