In the cold open in Park City, Kansas, a Museum and Gift Shop in the background has a prominent LED clock (7:34 and 32 degrees). In this time period, this clock would have had white incandescent bulbs, not red LEDs.
The light bar shown on the Altloona Police vehicle that takes Bill and Holden to the fiancee's house and is from the wrong time period. This style light bar is not used until at least a decade after the time frame in which the series supposedly takes place.
At the airport parking lot where Holden sees Dr. Wendy off, slightly inclined parallel marks on the light blue paint of the round concrete columns indicate they are likely wrapped with carbon- or glass- reinforced polymer sheets, a reinforcing technology that became mainstream in the 1990s.