One official at center signals a touchdown while another referee at right waves it off on what would be ruled a catch by Seahawks wide receiver Golden Tate, obscured, on the last play of a game against the Green Bay Packers on Sept. 24, 2012, in Seattle. (AP file photo)

The NFL’s last foray into replacement officials ended in embarrassment for the league when a botched call and comic confusion in a prime-time game led to the end of a lockout that marred the first three weeks of the 2012 season.

The play known as the Fail Mary proved to be the final straw that helped end that labor dispute, drawing such widespread criticism that even the two major presidential candidates weighed in on it. But it was far from the only instance of a blown call, a lack of understanding of rules and procedures, or question of impartiality.

“Would you let a Toyota dealership work on your brand new Rolls-Royce? That doesn’t work right, does it,” Dallas safety Gerald Sensabaugh said at the time. “Our brand is so big, it’s so important to a lot of people. There’s no way you can have guys that don’t have experience at that level.”

There weren’t as many glaring errors when the NFL also used replacement officials for one week of exhibition games and the opening week in 2001 before the labor dispute was resolved shortly after 9/11, and the regular officials returned in time when the season resumed following a one-week break.

Now the league is preparing for the possibility of another season starting with replacement officials. The NFL is moving forward with plans to begin hiring and training replacement officials in the next several weeks because negotiations with the referees’ union have been unsuccessful, two people with knowledge of the discussions told The Associated Press. Both people spoke on condition of anonymity because the conversations are private.

The NFL also passed a rule change Tuesday that would allow the replay center to correct “clear and obvious” mistakes if the league does use replacement officials, even on certain penalties that aren’t normally allowed to be reviewed by replay.

Here’s a look at some of the memorable mistakes that occurred the last time the NFL used replacement officials during a labor dispute:

Fail Mary

The final straw of the 2012 lockout came in a Monday night game in Week 3 that provided the indelible image of the three-week fiasco, with two officials signaling diametrically opposed calls at the same time.

With Seattle losing 12-7 with the ball at the Green Bay 24 in the closing seconds, Russell Wilson launched a deep pass toward Golden Tate in the end zone. Tate shoved cornerback Sam Shields out of the way and went for the ball with Packers defender M.D. Jennings. It appeared Jennings initially caught the ball before Tate tried to wrestle it away.

Adding to the confusion was the reaction from the two officials in the area. One waved his arms back and forth, signaling a touchback. The other signaled touchdown. The final call on the field was a simultaneous catch that resulted in a TD for Seattle and it stood after a lengthy replay review.

“It was awful,” Packers quarterback Aaron Rodgers said. “Just look at the replay. And then the fact that it was reviewed, it was awful.”

The league later said Tate should have been called for offensive pass interference, which would have ended the game with the Packers winning, but said there wasn’t enough evidence to overrule the call of a catch.

Las Vegas oddsmakers said at least $300 million changed hands worldwide on that call. The numbers would be significantly higher this season with the spread of legal gambling.

Calls in question

The night before the Fail Mary, another high-profile game in prime time ended in controversy.

Justin Tucker’s 27-yard field goal on the final play was ruled good, giving Baltimore a 31-30 win over New England. The ball was above the right upright and appeared as if it might have been wide, but was ruled good. The play wasn’t subject to replay because the ball was over the upright, but Patriots coach Bill Belichick wanted the officials to give it another look.

He grabbed the arm of an official and was later fined $50,000.

One of the big concerns about using replacement officials was player safety. One of the most memorable of those cases came in Week 3 when Pittsburgh safety Ryan Mundy delivered a helmet-to-helmet hit on Oakland receiver Darrius Heyward-Bey but there was no penalty. Heyward-Bey was hospitalized with a concussion and neck injury, and Mundy was later fined $21,000 for the hit.

Technical problems

Many of the issues in 2012 were more about procedure than the actual calls.

There was a Week 1 game between Seattle and Arizona when the officials gave the Seahawks an extra timeout because they incorrectly didn’t charge them for one after an injury in the final two minutes.

The 49ers were given two extra challenges in a Week 3 loss to Minnesota as the officials let coach Jim Harbaugh challenge two calls even though he was out of timeouts.