This marks the first appearance of the Ace of Clubs, which previously served as the set for Oliver's apartment in Queen Tower.
Chloe says the new page didn't "Rita Skeeter" itself into Swann's journal, a reference to Rita Skeeter, a questionable journalist witch from the Harry Potter novels. Rita uses a quill pen that writes by itself.
Clark mentions the red giant star next to Krypton. Krypton was a planet which orbited a red sun whose sunlight did not give Kryptonians the same powers as Earth's Yellow Sun. This has yet to be explored on the show.
In the episode "Lara", Kara mentioned it takes 3 years to travel from Krypton to Earth. If Kara sends her SOS message to Earth on 1986, it would make sense if Dr. Swann received it 3 years later in 1989.
The last scene of the episode where Clark and Chloe assume Brainiac went back in time to kill Clark when he was a baby, is similar to The Terminator storyline. A machine sent back in time to kill the last hope of man-kind before he fulfills his destiny.