There are multiple references to the character Juan Pablo being from Portugal. Both Juan and Pablo are Spanish names, not used in Portugal.
S1e1 ends with the song Smalltown Boy by Bronski Beat which wasn't released until 1984. S1e2 starts in December 1983.
The theme tune to This Is Your Life (1955) is heard in Colin's room, with the implication being that he's watching it on television. However, the episode is set in September 1981 and the latest series of This Is Your Life didn't begin until October that year.
A Batman comic book is shown on Colin's (Callum Scott Howell) nightstand underneath his alarm clock. It shows Batman having his back broken by the super-villain Bane, an event from the "Knightfall" storyline published in Batman comics between 1993 and 1994. However, the episode takes place in 1981.