Factual error: Throughout season 2 there are a few shots taken of buildings with PTZ style surveillance cameras attached to said buildings. PTZ cameras are the ones with an arm and a ball with a black lens spanning 360°. This show takes place in 1992, and from what limited dates as to surveillance camera creation I could find, PTZ cameras were not available until the 2000's. In 1992 the large blocky ones were only available with terrible resolution.
City on a Hill (2019)
1 factual error in Season 2 generally
Starring: Kevin Bacon, Aldis Hodge, Amanda Clayton, Lauren E. Banks
What They Saw in Southie High - S1-E2
Other mistake: Agent Rohr asks who the cold case is related to. A dossier is given to him and the front cover contains a photograph and the name "Kanicki, K". Agent Rohr says "Kelly Kanicki" but there was no indication of the full name, just the initial. (00:08:30 - 00:09:00)