Starting in the 3rd season Lois & Clark episodes began to make Batman references. In the season premiere Clark mentions Gotham City. Later in the episode with Jonathan Frakes and his wife as a millionaire collectors of rare objects, one of the actual Batmoblies featured in Tim Burton’s films is briefly shown in their collection. With a brief quote of Danny Elfman’s theme.
There are more casual references to Batman in other episodes. Without those above two could have been interpreted as mentions of fictional character. But they had already established Gotham and Batman exists and no later mentions are to him are inferred to be fictional at all.
The 3rd season debuted the fall of 1995. The same year Batman Forever. Which had Bruce mentioned to Dick that the Circus must be half way to Metropolis when he threatens to run away. I suspect the L&C writers enjoyed that an followed. Plus both Batman Forever and Batman & Robin were filmed on WB Burbank lot when L&C. I read years ago Dean Cain and George Clooney played basketball on shared breaks in production.
I can come up with a more specific list in a bit. On YouTube a fan created a Lois and Clark and Batman teamup trailer. Using audio from those scenes of Dean saying Batman, Gotham City. which adds much more legitimacy to it than most mock trailers do.
