Revealing mistake: When Andi walks into the library (this is not Andi's dream) it cuts to the librarian sitting at her desk and we can see the shot is flipped - note the bookcase and the librarian's buttons. (00:10:40)
Episode #1.3 - S1-E3
Audio problem: Elaine refers to someone's "ChatsApp" account, but her lip movements show she is actually saying "WhatsApp." (00:13:55)
Continuity mistake: When Evan is out with Doug it is day time. Evan proceeds to get out his cell phone to text Casey. Then we see Casey and it's nighttime. (00:11:50)
Episode #1.1 - S1-E1
Continuity mistake: The protagonist finally receives the Anmitsu, breaking his orgasmic trepidation. In the close-up, the tray is really close to the teacup, but in the following shot it's definitely further away, to the point that Kantaro in facts moves it to the right, in the same position shown in the close-up. (00:12:15)
Factual error: ACC Pat Gallan wears the ribbon of the Queen Elizabeth II Diamond Jubilee Medal. The medal was issued in 2012. Her medals would be correct for 2017 when the series was made, but not 2007 when it is set.
Boundaries - S4-E3
Continuity mistake: Alex and his mom are talking with Grandma about masturbation. Alex is in his school uniform shirt but for one shot he has a hoodie on, then in the next shot it's gone.
Continuity mistake: When Dr. Andrews tells Mrs. Cross via video chat that her husband has blood in his NG tube, the clock in the top left corner of Mrs. Cross' phone says 5:09. Two shots later, it has suddenly changed to 5:01. A few moments later it changes to 5:10, then back to 5:01 and then for some reason to 4:53 at the end of the scene.
Factual error: Johann Eck is dressed as a cardinal and Albrecht von Brandenburg addresses him as "Your Eminence" and kisses his ring. In reality, Eck was not a cardinal. Albrecht, however, was. It should be Eck showing deference to him, not vice versa. Albrecht was also only thirty, half the age of the actor playing him.
Episode #4.9 - S4-E9
Factual error: Renate escapes from the prison in a Morris Ten Four, with the badge visible on the bonnet. However, this designation was not introduced until 1935 and the episode is set in 1931.
Visible crew/equipment: When Adrian is getting something from the snack machine, the cameraman can be seen in the snack machine's reflection. (00:26:30)