Although the film was a box office disappointment in the United States, it was a huge hit in Asia. Quelque part dans le temps (1980) is one of the highest-grossing films in China, and played in Hong Kong for eighteen months.
While Christopher Reeve was filming this movie, the local theater decided to show his latest hit Superman (1978). Many of the "Somewhere" cast joined the locals for the event. Early into the screening, the sound went out. Reeve, who was seated next to Jane Seymour, stood up in the audience and delivered all the lines.
As of 2008, the numbers of Elise McKenna and Richard Collier's rooms do not exist at the Grand Hotel. However, there is a Somewhere in Time suite.
The film's recurring haunting theme music, selected by composer John Barry, was the eighteenth variation of Sergei Rachmaninoff's "Rhapsody on a Theme of Paganini".
The moment when Richard Collier first sees the portrait of Elise McKenna in the film was also the first time Christopher Reeve saw the portrait. Reeve did not want to see the portrait ahead of time, which helped meet the director's objective of getting a genuine reaction from him when he first sees the portrait as Richard.
Richard Matheson: The film's screenwriter and also its source novelist as an astonished man in 1912. (This doesn't qualify as a cameo, as only uncredited people are considered cameos, and Richard Matheson is credited on the end credits.)