Well, I'm not really agreeing to that. The 5th down basically handed CU a National Championship.
You might find this excerpt from CU Sports Information Director Dave Plati to be interesting:
As the annual anniversary for the “Fifth Down” game approaches (we actually play on the date—October 6—this year), the thing always surfaces in one way or another. This time, there was a reference to it in a Rocky Mountain News column by Bernie Lincicome. The column itself was about sports cheats, from illegal enhancers to taping sideline signals to air conditioning at the Metrodome. The passage about the ’90 CU-Missouri game read like this:
“Without that famous fifth down at Missouri, Colorado does not have half a national football title to boast of, one it has never offered to give back.”
But Bernie didn’t know that if there were any real cheaters that day, it was some in the Missouri football program. That’s the problem; some things fade away during time or just aren’t known by those who weren’t there. So I told him as he had never heard the story of the condition of Missouri’s Omni-Turf field, one which caused any one to slip if they weren’t in the right shoes. No one from Missouri made any effort to inform the opponent that they needed to bring a different kind of cleat. I have no doubts had we been wearing the same kind of show Mizzou had on, we would have left with a 48-10 win or something of that sort (as a point of reference, CU's tight end inexplicably slipped and fell at the 2 yard line to set up the 5th down series, when the endzone was wide open for him to just walk into). We were that good and had just finished playing perhaps the toughest non-conference schedule ever.
And as we’ve always said, which common sense dictates, had we known it was fourth down, we’re not going to spike the ball to stop the clock, we’re gonna run a play.
Missouri got even twice with CU, in 1997 when we had a touchdown called back for having 12-men on the field (when we had 11, the official jumped the gun, thinking he saw something he didn’t and blew the call), and one year in the men’s basketball tournament, when even Tiger coach Norm Stewart said they were the beneficiary of a cheesy foul call at the final gun that awarded MU two free throws that broke a tie, sending CU home to Boulder.