At the beginning of the film, the "Private Beach" sign is obviously being illuminated by a hidden light, and not by the match the guy strikes on it.
Though the film was made in 1955, it takes place in 1947. However, in the scene where Abbe, Barney and David are driving through town after their first visit with Angel in prison, most of the cars visible in the background are 1950s or late 40s models, including brand new 1955 cars seen in an automobile dealership window.
A fake issue of a real magazine at a news stand shows a cover in its now-iconic 1955 style instead of it's much plainer 1947 style. Also, another magazine is clearly dated in 1952, five years after the narrative.
After ordering David to put Angel on the stand following their argument in his office, Barney walks out, leaving Abbe and David alone. Abbe turns to David and says, "Oh, Barney, there's a new world coming", when she certainly meant to say "David".