A trailer is all that Ireland has seen of Hollywood’s latest romantic comedy, but that has been enough to declare an Irish accent emergency.

Wild Mountain Thyme stars Emily Blunt and Jamie Dornan as star-crossed lovers – and farmers – on an emerald isle posing as Ireland.

Dornan’s characters talks to a donkey and trips into a lake while Blunt, her hair turned auburn, stomps around fields.

Gobsmacked reaction on Wednesday speculated that the film, to be released next month, would outdo Tom Cruise’s 1992 drama Far and Away for paddywhackery cliches and dodgy accents.

“Even we think this is a bit much,” tweeted the National Leprechaun Museum of Ireland, as a social media pile-on gathered steam.

“There’s fashion police, grammar police, we even have airport police. Is there such a thing as accent police?” tweeted Dublin airport. “If so somebody better call ‘em. On the upside Ireland looks nice.”

Twitter critics said Dornan had little excuse for a ropey accent since he was from Northern Ireland.

Filmed in County Mayo, Wild Mountain Thyme stars Christopher Walken, as the father of Dornan’s character, and Jon Hamm, who plays an American and thus escapes accent scrutiny.

The Irish Times film critic Donald Clarke had a question for the director, John Patrick Shanley: “What in the name of holy bejaysus and all the suffering saints is this benighted cowpat?”

The film could turn out to be a masterpiece but the trailer suggested national stereotyping on a par with Frenchmen bearing onion necklaces and Mexicans sleeping under sombreros, said Clark.

The Irish embassy in Washington DC was tongue in cheek. “To be fair, Irish accents are hard (we struggle with them at times),” it tweeted. “But otherwise #WildMountainThyme looks great. And, in Jamie Dornan & Emily Blunt, presents a remarkably realistic depiction, visually at least, of the average Irish man & woman. Truly, we are a beautiful people.”

Shanley, an Irish American from New York, adapted the film from his play, Outside Mullingar, that ran on Broadway in 2014. He won a best original screenplay Oscar in 1988 for Moonstruck.

• This article was amended on 12 November 2020 because a tweet by Dublin airport was misattributed to the Dublin Airport Authority.