Anachronisms: Acker Bilk's "Stranger On The Shore" is played at the town celebration. The song was a hit in 1962 and although it was written earlier, it was certainly not written as early as 1951.
Continuity: When Peter first arrives in the city, he has a big gash on his forehead but shortly thereafter the gash disappears.
Anachronisms: The siren speaker on the police car is a Federal Signals electronic speaker that was not introduced on police cars until the mid-'60s. Sirens of the era of this movie would've been electro-mechanical wind sirens.
Anachronisms: The diesel locomotive pulling the train that Pete is riding back to Lawson near the end of the movie is a later model Electro Motive Division GP (general purpose) engine that was not available until the mid-60s. Diesel engines were certainly available in the early-1950s, but not that model.
Errors in geography: When Pete wakes up from the car crash on the beach it is early morning and the sun is shining but as he walks on the beach his shadow falls on the east, away from the sea, indicating the sun is in the western sky. This is typical late evening light on Pacific Ocean beaches
Continuity: When Pete returns to Lawson at the end of the movie, the sun moves around between shots.
Continuity: When Harry and Peter are in the auditorium of Majestic together for the first time and Harry is explaining the Majestic to Peter, Harry's shirt collar changes from being inside of his sweater to outside of it between shots.
Continuity: When Leo Kubelsky is talking with Peter Appleton as they walk through the studio Lot, as Leo Kulbesky announces that the "studio has suspended negotiations this morning," the shot shows Allen Garfield with a modern "in-ear" hearing aide. The rest of the time he is shown with out it.
Revealing mistakes: When Peter wipes the smudge off the glass over his name on the glass case containing the movie poster at Graumann's, the studio serial number is "51/340" on that poster. When Sand Pirates of the Sahara appears several weeks later at The Majestic, the poster across from the concessions stand is also "51/340" - it's highly unlikely the same poster from Graumann's would end up at The Majestic. Further, it's also too coincidental that the this one copy of probably six sent would end up in the same approximate location in both theaters - in the interior poster holder across from the concessions stand.
Anachronisms: In Mabel's Diner, the catsup bottles have the rounded metal, quick twist tops. In the early fifties, the tops were a cylindrical design with vertical ridges to aid with grip.
Anachronisms: The movie is set in 1951, yet Harry tells Luke/Peter that he has been gone for 9 and a half years. If Luke had actually died in 1944, shortly after D-Day, the correct setting for the movie could have been no earlier than 1953 or 1954.