An entertaining encounter at Santiago Bernabeu on Tuesday included a bit of everything – extra-time, six goals, a red card, a hat-trick and various records being broken.
Ronaldo reached the most notable landmark, as he became the first man to hit 100 goals in the Champions League, but he benefited considerably from two questionable offside calls.
Those decisions helped to alter the course of the tie and former Bayern midfielder Hargreaves believes football at the very highest level should not be encountering these age-old problems in the modern era.
He told BT Sport: "Why do we not have technology in football? It is unacceptable.
“To have that many decisions go wrong at this magnitude. This game was decided by the referees."
Ronaldo’s treble helped Madrid to a 4-2 victory on the night and a 6-3 success on aggregate.
The reigning European champions now march on to the semi-final stage of Europe’s premier club competition, looking to secure back-to-back crowns under Zinedine Zidane.
They will, however, face questions regarding the manner of their progress.
On top of Ronaldo’s offside efforts, Bayern will also feel unfortunate to have been reduced to 10 men six minutes from the end of normal time.
Arturo Vidal appeared to have won the ball in a challenge with Marco Asensio, but he was shown a second yellow card and Bayern’s dreams ultimately disappeared with him down the tunnel, while Madrid midfielder Casemiro seemed fortunate not to be sent off.
Video technology is currently being tested by FIFA, with Real having seen the system used during their successful Club World Cup campaign.
It is also being used in the Australian A-League at present and will appear at the Confederations Cup in Russia this summer.