A part of Kovac’s backstory was filmed:

“One of the guys, when asked about the film, admitted that he was
unfamiliar with the novel but lamented that he’d heard how much fun
everyone in the business was having on the movie and that he’d only
worked on “one small scene” — one that he would get screen credit for
and was lucky enough to be given a line. His name is Tom Bardach. Asked
about the scene, he went on to say that it was nothing. That they’d put
him in a 50s look (hair and wardrobe) and that he was on a bed kissing
this girl when a kid walks in.”

http://www.comicrelated.com/commentary/watchmen_080605.html [1]