Blooper

There is no such golf competition as "The British Open". It has always been known as just "The Open" - as it was the first, and only. Other countries may have their own local open championships, such as the "US Open", which always has the host nation's name to indicate that they are not the original.

The airplane tickets are from "Atlantic Highways," but a PanAm plane is shown landing. It's possible Atlantic Highways was the name of the company the tickets were acquired through/provided by, not the name of the airline.

After Maurice returns home from the 1976 British Open (which is held in July every year), the twins are seen dancing to the ABBA song 'Money, Money, Money'. That song was not released as a single until November that year, and even the album it was taken from, 'Arrival', was not released until October 1976. However the track was actually recorded in May 1976 therefore it did technically exist at the time of the events. So it is up to the individual as to whether this is a true goof or not.

"Ride Like the Wind" by Christopher Cross, released on Cross' 1979 debut album, is heard in a 1978 golf course scene.

The beginning of the movie shows what looks like an old globe and zooms in on an old map to Maurice childhood. However the map borders and countries are modern from today 2022.