Zac Efron’s 17 Again has topped a list of 2009's Most Gaffe-Prone Films.

The survey, by film website moviemistakes.com revealed that the comedy, about a man who gets the chance to rewrite his life by returning to his youth, contains almost 100 goofs and continuity errors.

Harry Potter and the Half-Blood Prince and Transformers: Revenge of the Fallen tie for second place with 71 blunders.

Night at the Museum: Battle of the Smithsonian and The Twilight Saga: New Moon round out the top five, with 29 mistakes each.

The survey also revealed that 2012 has 27 errors while Nicolas Cage's sci-fi blockbuster Knowing has 25.

Overall, film fans spotted more than 900 gaffes in movies released during 2009.

"This isn't meant to be assigning blame - generally these are noticed by the biggest movie fans, even in films they loved. That said, you wonder how some of these blunders get past the editing room," the Daily Star quoted Moviemistakes editor Jon Sandys as saying.