20 Things You Didn't Know About Heat
3. Michael Mann Considered Having McCauley & Hanna Kill Each Other At The End
While shooting Heat, Mann heavily considered filming an ending where both Hanna and McCauley mortally wounded each other during their climactic gunfight, rather than Hanna simply prevailing over McCauley as occurs in the final cut.
Mann ultimately decided against the idea for whatever reason, and considering that their dual demise might've been a little too cute and obvious for its own good in terms of hammering home the cop/criminal duality, it was probably the right call to make.
As it stands, the ending to the movie is pretty much perfect.