There is a scene in the film SWING SHIFT in which a vehicle pulls up to a stop sign and the camera holds on the stop sign briefly. The stop sign has the colors in use today, white lettering on a red background. However, this color scheme on stop signs was not used until 1954. The film time period is during World War Two and just after. Of course that war ended in 1945. From 1924 until 1954 the colors for stop signs were BLACK lettering on a YELLOW background. For a true time period setting this was a blooper.