The film grossed more than US$200 million at the Chinese box-office, becoming the highest grossing movie of all time in China when it was released. It was the first movie in China to earn over a Billion Yuan, overtaking Titanic which earned around 975 million yuans in a decade.
The story begins with a scientist, Xu Lang (Xu Zheng), who invented a solution (youba, lit. Oil Master, translated as "Supergas") which has the power of increasing the volume of any liquid to which the solution is applied. Such a solution implies great potential profitability if applied to gasoline or any precious liquid. However, he needs the authorization of Mr. Zhou, the biggest shareholder, in order to get further funding from an investment fund. Gao Bo (Huang Bo), who was the classmate of Xu in college and his partner at the workplace, wants to sell the invention to a French company instead.
Upon the discovery that Mr. Zhou is in Thailand, Xu Lang immediately embarks on a trip to Thailand, constantly tailed by Gao. On the plane, Xu meets a young man named Wang Bao (Wang Baoqiang), who is going to Thailand to fulfill a list of dreams (including fighting a Muay Thai master, planting a cactus). Wang owns a scallion pancake store in Beijing, and claims that the famous actress Fan Bingbing is his girlfriend. Not wanting to be bothered by Wang, Xu keeps trying to get rid of him, but events unfold in such a way that the two become a team.
The two go on a hunt to find Mr. Zhou. The interaction between the savvy businessman and the pious, simple-minded chef is a source of most of the dialog in the film. Two to undergo major culture shock in Thailand, while Wang is frustrated with the progress in finding Mr. Zhou.
Attempting to blame Wang for the whole mishap, Xu finds cash in Wang's wallet. Considering that Wang lost all his money earlier in the trip, Xu Lang suspects that he is a spy for Gao and tears apart Wang Bao's diary. Xu goes on to read Wang's diary and discovers that Wang is writing tourist diaries attempting to cheer up his mother, who has Alzheimer's Disease, is a fan of actress Fan Bingbing, and wishes that Wang was in a relationship. Moved by Wang's diaries, Xu regains his trust for Wang.
Finally finding the temple where Mr. Zhou is supposed to be located, Wang encounters a Buddhist layman who brings a case which contains the authorization letter. The layman goes on to say that Mr. Zhou has indicated that it is up to them what they want to do with the letter. Gao shows up with a Muay Thai master (Saichia Wongwirot) and starts fighting to gain control of the case. Gao and Xu go on to fight frantically for the case, while Wang is overpowered by the Muay Thai master. Xu lets go of the letter and ultimately decides to fulfill Wang's wish of taking a picture of defeating a Thai boxer instead. Xu comes over and lies down and serves as his takeoff board. Stepping on Xu's chest, Wang flies up into the sky and defeats the Muay Thai master with a massive kick to the head.
Upon reading the letter, Gao goes on to find out that they need to cosign the authorization letter to validate it. At this point, Xu discovers that he does not care about the letter anymore, and he feels guilty for not having given enough attention to his wife (Xu Zheng's real-life wife Tao Hong) and daughter. Through the trip, Xu goes through a metamorphosis from a callous, manipulative businessman to an epiphany of what is really important in life. Wang, on the other hand, inadvertently fulfills every single one of his dreams during the trip in Thailand.
Towards the end, Xu reunites with his wife and brings the family back from the brink of divorce. Wang actually meets with the real Fan Bingbing through Xu's arrangement. Fan is moved by Wang's love for his mother, and agrees to take pictures with Wang inside a studio. Gao, still trapped in Thailand due to the loss of his passport which was stolen by Wang earlier, is happy hearing his wife giving birth to their baby over the phone. The story ends on a positive note.
The film premiered on December 12, 2012. On January 1, 2013, the film crossed over the 1 billion yuan mark, the first Chinese film to do so. It had previously beat James Cameron's 3D re-issue of Titanic which grossed RMB975 million and previous Chinese record holder Painted Skin: The Resurrection which had grossed RMB727 million. Cameron's Avatar still holds the record as China's highest grossing film, with RMB1.39 billion (US$223 million) on release in 2010 but Lost in Thailand has already overtaken the 3D film by number of tickets sold.
Variety wrote that the film is "lightweight entertainment" and "is no masterpiece, but has proven a refreshing antidote to the year-end glut of blockbusters" and it is "unexpectedly well honed for a debut feature."
Derek Elley of Film Business Asia gave the film an 8 out 10, and states "The chemistry between leads Xu Zheng and Wang Baoqiang that made Lost on Journey (2010) one of the most delightful sleeper hits of its year survives happily intact in Lost in Thailand", and "Thailand is in every way a much more commercial package. There's less depth to the new characters, the humour is more overstated and less grounded in reality, and overall the movie packs less of an emotional punch in its latter stages; but it's more slickly tooled and less digressive in its construction, halting on its path only briefly to review the plot and the central relationship."
According to Wall Street Journal, "The film’s success has shaken up the landscape of the movie industry in China, where big-budget historical epics and martial-arts and action films often dominate the box office."
Following the movie's release, tourism from China to Thailand skyrocketed, growing 60% in both 2012 and 2013.