Just like Sylvester Stallone wasn’t the original choice to play John Rambo, Richard Crenna wasn’t the original choice to play Colonel Trautman either. That role originally went to Kirk Douglas and character posters were even (officially) drawn up.
The day before filming began, at the 11th hour. Douglas, in a bout of extreme chutzpah, showed up with a revised script. He had the ending completely changed. Said Sylvester Stallone earlier a couple of years back:
“The plan to include Kirk Douglas snowballed into something I never expected. He said to me: ‘Here’s what I want. At the very end of the movie I should kill you. The audience sees a cop car driving away and as it disappears into the fog a hand reaches up to the rear view mirror. The camera turns up and we see me. It turns up a bit higher and I’m wearing your headband’”.
When Douglas was advised in no uncertain terms that his suggestion was not going to happen, he abandoned the shoot, leaving them in the lurch with one day to go. And with one day to go, Richard Crenna was drafted in.