Episode #1.1 - S1-E1
Factual error: This is set in 1933. When the killer comes back to his lodgings in episode 1, Lily on the stairs is humming "Somewhere over the rainbow", which was written for The Wizard of Oz in 1939. She also happens to wear bright red shoes, which feels like yet another Wizard of Oz reference. Interesting enough, the subtitles say that she is humming a different song, "Night and day" which she openly sings throughout the series and was already a hit in 1932. (00:44:10)
Factual error: The Saturn in the show is an Ion which stopped production in March of 2007. Therefore, it couldn't be a silver 2009 Saturn they were looking for.
Hit and Run - S4-E8
Factual error: Tim says, "At approximately 1057 hours" for the scene, but in the scene, it's shown the time is 10:14. The time should have been said, "0957 hours" for when the suspect attacked Nolan and Harper. (00:13:00 - 00:13:22)
The Day Danger Walked In - S3-E5
Factual error: Higgins, Thomas, TC and Rick are locked in a freezer. Their barber friend is tapping his horn in "a pattern" Higgins says is Morse code, and announces that he tapped "move back." Not really. I know Morse Code. All I got (along with a few undecipherable things) was TOERT NMU ETM CEA OFJ DER WK. No way that spells "Move Back."
Episode #1.6 - S1-E6
Factual error: When Commander Anne Sampson appears in her body armour she wears the rank insignia only worn by the Commissioner (a crown over a pip over crossed tipstaves in a wreath) instead of that worn by her own rank of Commander (crossed tipstaves in a wreath). She has apparently been promoted four ranks.
Factual error: When the Radio DJ is talking about the ATF raid, he is wearing a pair of modern Audio-Technica Headphones.