Clark always wears blue and red clothes (or at least one of these colors). No surprise that when he got his Superman costume, he chose those same colors.

Despite many hours of outdoor farm work, Clark never gets a tan or a sunburn. In fact, Tom Welling, who plays Clark, is contractually forbidden from getting a tan, because the show creators were not sure if Kryptonians could tan.

In the episode where Clark is lured to the asylum when Lex is with some of his former enemies, Jonathan Taylor Thomas' character taunts Lex while holding a newspaper with a headline starting, "Themysciran princess" and some other words. That is a reference to Wonder Woman, who is from Themyscira.

Annette O'Toole who plays Clark Kent's mom also played the role of Lana Lang in the Superman III movie.

Michael Rosenbaum is the only actor to play both an enemy and ally of Superman in two separate TV series at one time. In addition to playing Lex Luthor in "Smallville," he is also the voice of The Flash in the cartoon series "Justice League."

In the Episode "Flash" when Clark confronts the Flash in his hotel room, he reads off the fake I.D.'s Jay Garrick, Barry Allen and Wally West. Those are the secret identities of the first three men to be called the Flash. Also, this Flash says his name is Bart, like Bart Allen, the teen hero formerly known as Impulse and currently being called "Kid Flash."

At least two of the episodes in the series, "Shimmer" and "Jinx", are named after DC villains. Although they never fought the Man of Steel himself, both of them have fought Indigo, an android with some of Superman's DNA fused to her.

In the episode where Aquaman appears, he says, "We should start a JLA," (Junior Lifeguards Association). This is funny because he and Superman are later on a team Justice League of America.

Terence Stamp voices Jor-El in the Smallville series, and he also played General Zod in Superman II.

The Smallville Torch that Lex views on the internet has two articles that refer to past episodes. Pete wrote an article about his trip in a limo called Take Yourself Out Of The Driver's Seat ("Hourglass") and Chloe reprinted The Most Controversial Speech Ever Given In Smallville by Lana's mother ("X-Ray").

When Lex visits Cassandra and asks her to see his future, she sees a vision of him in the White House. This is a reference to the modern-day Superman comic books, in which Luthor is now the U.S. president.

Throughout this episode, the Superman theme tune can be heard at various points being played very softly and slowly. The first time it is heard, it is only the first few opening keys, but the last time it is heard, it is fully played.

All the music in this episode is by the band REM. Which is fitting as REM stands for "Rapid Eye Movement", the deepest part of sleep, where dreams occur.

At the end, when Clark is visiting Alicia's grave, there is another grave shown with the name Allison Dunn on it, which is the name of Smallville's set decorator.

Martha makes a remark suggesting she thinks Bridgette Crosby and Dr Swan are together to which Bridgette comments "In another lifetime." Bridgette is played by Margot Kidder, who played the original Lois Lane, Prof Swan was played by the late Christopher Reeve. A nice touch I think.