It's hard to believe it's been more than 20 years since the wrinkle-free Jim Carrey and the boyish Jeff Daniels put on their stupid faces and went on a really mindless adventure as dumb buddies Lloyd Christmas and Harry Dunne. The year was 1994 – when Carrey also made Ace Ventura: Pet Detective and The Mask, rocketing him to international comic stardom. Daniels had already made a name for himself on stage and screen – both in comic and serious roles – and after Dumb and Dumber he got smarter and smarter in films like The Hours and Good Night, and Good Luck.

The writer/directors of the original D&D film, brothers Peter and Bobby Farrelly, have passed the intervening years making a name for themselves with more slapstick-toilet bowl humour in films like The Three Stooges, There's Something about Mary and Shallow Hal.

Dumb and Dumber To continues the antics of the brainless duo as if nothing happened in between movies. In fact nothing did, mainly because Lloyd played a trick on Harry by spending 20 years in a mental hospital pretending to be comatose. Good one, Lloyd.

Upon release, the old friends quickly get entangled in a slapstick-driven chase across the nation to find Harry's daughter Fanny (Rachel Melvin) who was adopted out at birth by her mother Fraida (Kathleen Turner). Raised by world famous scientist Dr Pichelow (Steve Tom), Fanny is on her way to a technology conference to give a speech on behalf of her father. Pursuing her is not only the dumb duo but Pinchelow's gold-digging wife Adele (Laurie Holden) who wants to kill both daughter and father for the money.

The crazy narrative is really just a ropey clothesline for Carrey and Daniels to hang out their gags – some as dirty as ever – but most delivered with the affable good-natured lunacy that you'd expect from the Farrelly brothers. And, as they have deliberately neither updated the style of the film nor messed with the much-loved characters, there's a tired edge to proceedings, as when old friends refuse to grow up and try to amuse you with the same joke you've been hearing for years.

Carrey's performance – which carried the novelty of the first film – lacks its manic sharpness, and at 109 minutes the film is just too long to sustain the stupidity. But there are moments of genuine – albeit very dumb – humour, the best scenes involving fantasy flashbacks as Lloyd and Harry imagine how things might have been different if they'd actually done something with their lives. Fans of the first film will love these far more creative touches. The film ends suggesting the next sequel, Dumb and Dumber For, will be available in 2034. I'm happy to wait.