A police barricade in 'Jacksonville' says "DO NOT CROSS", foreshadowing the conflict between Nina, Carla, and Walter as Nina and Carla try to stop Walter from crossing universes in 'Peter'.
Two Observers in 'Peter' exit a movie theater displaying a poster for "Clue", foreshadowing the title of 'Olivia. In the Lab. With the Revolver' and the confrontation between Olivia and James Heath.
WALTER: "Do you know how many times William has encouraged me to take this very risk? To expedite our espionage program. 'Why simply take a peek into the other universe, Walter, when you can go there?'"