Did you know that an arrow on a sign in Jurassic Park changes directions and that the trails of the Maverick missiles fired at a bridge in True Lies looked obviously computer-generated? Well, avid film-goer Jon Sandys spotted those gaffes, noticed there was nowhere on the web that focused on cinematic errors... and Movie Mistakes was born. He launched the site a dozen years ago and has gone on -- with the help of his members -- to detail tens of thousands of errors in 5,700 films (and counting).

So far, Apocalypse Now wins the prize for most mistakes: 395 to date. And Star Wars contains the most egregious error, according to the site's fans -- there is no corresponding noise when a stormtrooper hits his head on a door frame. (The oversight was corrected in the film's DVD release.) The site stays current: Recent releases Forgetting Sarah Marshall, Nim's Island and 88 Minutes are already accounted for.

Movie Mistakes generally gets about 3.5 million visitors a month, though traffic tends to increase when the big summer movies  -- "often fairly mistake-ridden," Sandys notes -- are released. It has gone from solely featuring movie mistakes to including TV mistakes and movie and TV trivia, and now the site's "slowly expanding into a general movie resource, with quotes and trailers too, but I don't think I'll ever really take on the major movie sites as they've got better resources," explains Sandys. The content, generated from contributors around the globe, is not verified, though everything can be corrected or removed. Sandys asks potential contributors not to submit only mistakes they have personally seen on film.

Sandys has parlayed the website into quite a career, with seven books about movie mistakes, TV mistakes and movie trivia. His favorite films include Star Wars, The Godfather, Grosse Pointe Blank, Kiss Kiss Bang Bang and anything by Tim Burton, while Robocop 3 and Batman and Robin are particular targets of his ire because "they each took a promising and enjoyable franchise and destroyed everything that made them good," he says. Sandys, who lives outside London, England, has received criticism for trying to undermine the film industry with his website, but he believes the site is a testament to his love of films. "Spotting mistakes only ever came about as a result of watching lots of films," he says. "While on occasion there can be a bit of pride, I suppose, at spotting something which may have slipped past the editors, it still comes from interest in movies rather than criticizing the quality."