Superman Returns played a role in how Smallville handled Clark's love story with Lois Lane. When Bryan Singer’s DC movie hit theaters in 2006, Smallville was still in the midst of its ten-season run. At the time, the Superman prequel series was between its fifth and sixth seasons. At that point in the story, Kristin Kreuk's Lana Lang was still Clark's love interest on the show.
Comments made by Smallville creators Alfred Gough and Miles Millar reveal that while Smallville and Superman Returns weren’t in canon with each other in any way, DC's movie plans did result in limits being set on what the writers of the show could do with Tom Welling’s character. Millar said in 2007 (during season 6) that DC was unwilling to allow Smallville to touch Clark and Lois’ romance [via ComicsContinuum]. It would seem that this restriction was related to the importance of their movie counterparts’ love story in Superman Returns. Sequels were still on the table at that point, which explains why DC was opposed to this relationship playing out on TV at that time.
How Smallville Teased Clark & Lois’ Romance Before Season 8
Smallville may not have been allowed to use their iconic romance from DC Comics until season 8, but whatever limitations it had didn’t prevent Smallville from alluding to it. Romantic feelings between the two were avoided altogether between seasons 4 and 7, but it seems certain teases were permitted nonetheless, not unlike how it included various references to Clark’s future as Superman. One such moment was in “Hydro” when Clark, dressed up as Green Arrow, was kissed by Lois. Afterward, she admitted that the Green Arrow imposter could teach her then-boyfriend Oliver Queen “a thing or two” about kissing, not realizing that she was actually talking about Clark.
Exactly what Smallville would have done with the two characters had these restrictions not been in place is unclear, but keeping Clark and Lois' friendship purely platonic for four seasons allowed the series more opportunities to explore his relationships with Lana. Instead of dropping the romance with Lana or creating a love triangle between the three, Smallville found other ways to move forward. For better or worse, the series greatly extended Clark and Lana's relationship woes, and by having Lex come between them in season 5, it made their romance an important part of the character's villainous transformation.
How DC’s Movie Plans Effected Smallville
Clark and Lois’ romance being delayed by Superman Returns wasn’t the only instance of Smallville’s story being governed by DC’s movie plans. It’s no secret that Gough and Millar were interested in using Batman, but Christopher Nolan’s The Dark Knight trilogy stood in the way of the Caped Crusader stepping foot in Smallville. And while no Wonder Woman movie was made in the 2000s, DC’s intentions to give Diana Prince her own live-action film meant she was off-limits as well. All of these characters being held back by DC resulted in Smallville making use of characters like the Flash and Green Arrow, who weren’t expected to jump to the big screen at any time in the near future.