Media firms can be tricky too, because in our modern world much of our social interaction takes place online. If you go for accuracy there's a good chance your date film will date in a very different way, so for example You've Got Mail's love affair with AOL seems rather odd today, and we're sure anything with Facebook in it - The Social Network aside - is going to seem equally odd a decade or so from now.

Missing mobiles

As not seen in: Blade Runner

With the honourable exception of Star Trek, whose Tricorders and Communicators were smartphones in all but name, Hollywood often goes for what looks interesting on screen rather than what people are likely to use

So, for example, in Blade Runner, the future's favourite communications system was a public videophone rather than a cellphone. Blade Runner did go on to inspire real-life phones, though: Google's Nexus One takes its name from the androids in the film.

The lack of cell phones in films already seems odd: as The Guardian's Joe Queenan writes, the rise of the smartphone means that "plotlines that were completely plausible as recent as 10 years ago are no longer plausible now" [http://www.guardian.co.uk/film/2011/jul/28/technology-killed-film-plots-hollywood].

Really awesome numbers

As seen in: Johnny Mnemonic

It was pretty cheesy back in 1995, but these days the Keanu-starring, William Gibson-adapting Johnny Mnemonic is even funnier - particularly the scene where he doubles his on-board storage capacity from 80GB to a whopping 160GB.

Like Dr Evil's "One... million... dollars!" in the Austin Powers movies, Keanu's numbers haven't kept up with inflation: 80GB may have been a mind-boggling amount of data in the mid-1990s, but these days it's a couple of flash memory chips.

Lame CGI

As seen in: The Matrix Reloaded, The Mummy Returns, Die Another Day, Spider-Man...

As CGI gets better, our tolerance for bad CGI diminishes - so if you watch something like the Matrix Reloaded's famous Burly Brawl ten years on, it's rather like watching someone playing a recent Xbox game.

There's no shortage of examples: the stampeding dinosaurs in King Kong, the Scorpion King in The Mummy Returns, the surfing scene in Die Another Day, the Green Goblin in Spider-Man... the list goes on and on and on.