The Batman universes of Tim Burton and Joel Schumacher have a couple of similarities but also a lot of differences, but there’s one Arnold Schwarzenegger Easter egg in Batman Returns that could link both universes. After a film adaptation of the 1960s TV series Batman, the Caped Crusader returned to the big screen in Tim Burton’s Batman, in 1989, with Michael Keaton playing the title character. The success of Batman made way for a sequel titled Batman Returns, and while it’s now regarded as one of the best superhero movies ever made, its tone was too dark and the studio decided to go in a different direction for its third Batman movie.
https://screenrant.com/batman-returns-mr-freeze-arnold-schwarzenegger-easter-egg/