tl;dr: The copy <PERSON> watched had been damaged and repaired. In order to repair the film, the projectionist cut out the part of the film with the beginning part of that line.
There's no way for me to prove this definitively, but I have a pretty good idea what happened.
I was a projectionist at a movie theater for a few years in the late 90s/early 2000s. This was before movies were projected digitally. At that time a movie was delivered to the theater on four to six reels, which we then built up into one continuous reel on a large platter next to the projector.
To play the film, we had to thread the film through a "brain" in the middle of the platter that controlled the speed of the platter as the film showed, then through a series of rollers, as well as the projector itself. The beginning of the film was then attached to a ring on another platter so as the film played, the used film would wrap back up so it could be re-threaded and re-shown at the next showing.
Now, there are a lot of opportunities in this <PERSON>-like setup for something to go wrong. The most common problem was static electricity would cause two layers of film to stick together. 813
They would get drawn into the brain causing a jam which breaks the film. Another common problem was the film would sometimes jump one of the rollers on the outside of the brain and get hooked. This would cause the film to wrap around the brain until it tightened enough that the film could no longer get drawn through. The film would stop in the projector and the heat of the bulb would melt it.
To fix the film when it breaks this way, you have to cut the damaged section of film out, and splice together the two ends of the remaining film. Depending on how damaged the film got, you could cut a few unnoticeable frames out, or whole seconds or even minutes of film. This usually didn't happen to a film within the first few weeks of showing it, but a very popular film that stayed in the theater for months might get damaged several times.
I don't remember how long Batman (1989) was in the theater, but I wouldn't be surprised if it stayed for months. It's very likely that Tango saw a copy of Batman that had been damaged right at that iconic scene, and the projectionist had cut out the beginning part of that line and spliced it back together in order to fix it. 813