Memento may be Nolan’s breakout film, but his best known films to date are still The Dark Knight trilogy.
Eerily, Memento gives a nod to the character that would make him a household name, with the a Batman logo appearing in a store window about halfway through the movie. This wasn’t even the first time that the Batman logo appeared in a Nolan film.
As for Memento, the window also features the Superman emblem, a Star Wars logo and some other fan-centric graphics, so it likely was a comic book store window.
In an interview with Empire (via Film Detail), Following actor Jeremy Theobald said that the Batman logo was there because they filmed that scene in his flat and he had the Batman logo there since 1989, when Tim Burton’s version came out.