Observe the trailer above: it tells you pretty much from the outset that this is a comedy – it’s going to be one of those dash-everywhere-oh-my-god-can-they-do-it, rather like the last 10 minutes of Notting Hill (hope that doesn’t ruin it for you).

If you look an early version of the poster (here at Coming Soon) then you get the message straight away: Comic Sans font! Hey, it’s a laugh!

If you went by the trailer, or the Comic Sans font and the rib-nudging tagline, you’d think that The Concert is just a bit of comic nothing – an easy way to pass 90 minutes or so.

No. Completely not. It’s a terrific film which packs a huge emotional punch in a closing section which has no dialogue at all but explains all the loose ends in the story. (There’s a question about whether some of what you see in that section is a flash-forward or just an ambition – I think it’s a flash-forward which, for reasons of keeping the ending tidy, had to be put before the climax).

Don’t just believe me – IMDB, the movies database, is a reliable guide to what people think of a film. And people there give it 7.5/10 (I’d give it higher, personally).

It’s one of the rare examples I’ve seen where the trailer gives you no idea of the emotional power of a film; it makes it look like a silly comedy, but it makes many more points – some of them in comic fashion, sure, but the heart is serious.

It’s unusual, isn’t it, for a trailer to undersell a film? Before seeing The Concert, I saw the trailer for Knight and Day, the Tom Cruise/Cameron Diaz effort – trailer here (no embedding allowed, it seems). But people on IMDB give it 6.6. Every time I’ve seen the trailer, I’ve thought “I’d like to see that film. Looks fun. Cruise not taking himself too seriously.” Apparently not, going by the people who’ve seen it.

So do you know other trailers that have undersold the film? Do tell. Obviously, reference to IMDB to prove that it’s a great film may be needed…