Champions League: Rules expert explains game-changing 'errors' in Real Madrid's comeback over Bayern Munich

The fallout from the linesman blowing his whistle early and wiping out what would've been a Matthijs de Ligt goal for Bayern

In one of the most epic Champions League semifinals in recent memory, Real Madrid produced another late UCL comeback, scoring twice in the final minutes to beat Bayern Munich 2-1 at the Santiago Bernabeu. It was Joselu who came off the bench for a brace, seeing the Spanish club advance 4-3 on aggregate, and they'll take on Dortmund in the final on June 1. 

But it wasn't without massive controversy.

As Bayern pushed forward in need of an equalizer to force extra time, defender Matthijs de Ligt found the back of the net with a brilliantly struck low shot from inside of the box. The only problem? The assistant referee put his flag up and called offside on the long ball preceding the Dutch defender's shot. De Ligt and teammate Noussair Mazraoui went up for a long ball into the box and appeared onside. Instead of keeping his flag down and letting the play continue, the assistant referee called the offside, the ref whistled it, and the play was called dead. That meant that it could not be reviewed as Real Madrid players stopped playing before the shot went off.