Factual error: There is a periodic table shown in the background of the lab, showing an accurate periodic table as of now. During 1945, at least 21 elements had not been discovered. (00:17:40)
Factual error: The Marine Colonel in Supergirl played by Eddie McClintock spends all of his time wearing Marine Officer's Dress Blue Bravos. Marine Dress Blues are ceremonial uniforms. On rare occasions, the Charlies or Deltas (no coat) may be worn as a work uniforms (the primary exception to this rareness being recruiters). The full uniform is certainly not worn for day to day work in the field.
Factual error: 1-1 A couple of spelling errors. A "community center" in Ceylon, a British colony, using the American instead of the British spelling. And Columbo listed as the capital of Ceylon; it's Colombo.
Factual error: The police car license plates shown in the episode have a 2 digits-1 letter -2 digits pattern, while in reality they follow a different one (one letter and then numbers only).