Colorado did get a 5th down
Yes
and it helped them win the game along with some other questionable calls in the last final seconds against Missouri.
1) 1990 was the first year of the new 'spike it' rule - prior to that a QB had to throw the ball out of bounds to stop the clock.
2) Colorado did this TWICE in the five plays. They only actually TRIED to score three times.
3) Colorado got confused as did everyone else including the officials, partly because of the new rule and partly because there was a guy behind the down marker folks dying of a heart attack. The officials did not catch the problem, but that's not Colorado's fault.
4) The biggest problem is that
MISSOURI KNEW IT WAS FIFTH DOWN AND DID NOTHING ABOUT IT!!!! Missouri's assistants were telling head coach Bob Stull that the spike was on fourth down and he could have called timeout. He chose not to do so - the reasoning afterwards being the hope they could stop CU again.
5) After the Missouri game, Colorado dropped two spots in the polls despite winning. They were 14th in the poll of October 8, 1990, and nobody gave them a chance to win. They beat #22 Oklahoma at home and #3 Nebraska ON THE ROAD in back-to-back weeks. But on top of that they had to wait as Virginia lost TWICE, Miami lost, Notre Dame lost and so did Auburn and Michigan.
That CU team played the toughest schedule in the country and tied the SEC champs despite their best player (Eric Bienemy) not even playing, beat the Rose Bowl champs, the SWC champions, and two-loss Notre Dame.
The problem with "what if" arguments is that we're going to count a game in October due to a ref call against CU then why not call tying with the Vols without their Heisman Trophy candidate in their favor?
Note that I've come around on this issue because I used to say the same thing as many fans. It's true that if CU lost that game then it would matter but the flip side is that Colorado wouldn't have spiked the ball had they known it was fourth down, either.
They still had to go on and win the rest of their games that season, but a loss to Missouri would have put their record at 3-2-1 at the time and they would not have shared the 1990 national title that year with Ga. Tech.
Yes, a loss to Mizzou would have given them two losses BUT....what play do they call if they know it's fourth down when they spiked it? That's what makes the infamous Dartmouth-Cornell game different because Cornell tried to score on all five plays. CU center Jay Leuwenberg actually argued with Coach McCartney - when he was telling the backup QB what sequence to run - and told Mac that they didn't have enough plays to do what he was saying. Mac told him to shut up and play center so Leuwenberg decided he must have been that one to have gotten confused.
And speaking of that - does anyone seriously think that if Darian Hagan, the CU starter, had actually played the game that there ever would have been a Fifth Down? Colorado isn't given credit for beating the Alabama of that time frame (Notre Dame) with a backup QB in the Orange Bowl. Sure, Colorado got some breaks - Washington should have beaten them and blew themselves up and Notre Dame missed a PAT and had a Rocket Ismail return nullified by penalty.
But other teams had bad breaks that year, too. UVA was number one and their best players got hurt in the Tech game. 1990 is one of those weird years like 1984 and 2007 where nobody was really sure at the end if the champion was deserving but....they were still the champions.