Chloe (Allison Mack) sported a distinctive asymmetric hairstyle, a style Mack had adopted over the summer hiatus. However, it was felt that the look wasn't right for Chloe, so Mack wore extensions for the subsequent few episodes whilst her natural hair grew longer. Mack has often joked that no one in Smallville appeared to notice Chloe's hair changing length over the course of one episode.
In the commentary for this episode, it is mentioned that the pre-credit scenes of Clark having fun with the Red Kryptonite (Destroying ATMs, etc.) were added in a week before the episode aired. Gough and Miller were all for the idea as long as the network paid.
Terence Stamp, the voice of Jor-El, played Gen. Zod in Superman I & II.
While being erased, the mark on Clark's chest in the final split second resembles the "S" sign that Superman will wear in the future.
The actor Ryan Robbins that is "stranded" on the island with Lex also plays in Arrow(which also happens to be based off of a DC comic book character, the Green Arrow) season 4 where he is a guard of sorts that happens to be convening on the island Lian yu.