1 Joe Hart at the crossroads
At what point does a player become a liability? Following the latest schoolboy error to add to the catalogue Joe Hart is compiling, the answer may be the moment seven minutes in when Franck Ribéry pulled the trigger and City's goalkeeper let in the softest of strikes for Bayern to take a 1-0 lead.
This was the night when sections of the Etihad Stadium crowd turned on the keeper – with one fan delivering an ironic "well done Joe you useless bastard" after he took a regulation catch moments after he gifted Bayern the early advantage.
The case for Hart whenever a howler is committed is that there is no one else to touch him, whether for club or for England. But after Bayern's third beat him on the near post, Hart's stock now falls to the point where the side for Saturday's home match with Everton will be heavily scrutinised to see if his name is written on it.
2 The Bayern coach demands perfection
What must Pep Guardiola be like when his team play badly? The question arose before and after his side's first goal as the small man with the turned-up collar displayed unbridled frustration despite onlookers admiring the hiding his side were handing City.
Guardiola engaged in an argument with Arjen Robben, who was not doing his job properly during a hold-up for treatment to Toni Kroos. There were histrionics at Bayern not pouring forward fast enough, which happened early on whenever Rafinha, the visiting right-back, took charge of the diagonals delivered by David Alaba. The Spaniard continually paced the technical area with the air of a man who believes he is constantly viewing a game none of his team can yet see.
Ahead of the contest Guardiola stated he wanted to be like Manuel Pellegrini, right, for the consistent style-pattern he brings to every club he leads. After this, you understand why all the other coaches want to be like Guardiola.
3 Micah Richards' big return
The man who could yet be a late runner for a berth in England's World Cup squad (if qualification is managed) was handed a start in a major game for the first time this campaign.
A hamstring injury had limited the right-back to only one previous appearance – against Wigan –but when the team sheet fell it showed that Richards was selected on merit, given the nod by Pellegrini ahead of Pablo Zabaleta, who was on the bench. As with all players in the sky blue livery, Richards struggled all evening, with a header from a Samir Nasri cross that was aimed straight into Manuel Neuer's hands and the flat-arming of Toni Kroos his only notable contributions.
Yet this was against a side who are the continent's benchmark and the experience of facing the relentless Bayern red wave should strengthen Richards as the long winter months approach.
4 Manchester City are schooled
To line up against the Champions League holders of Ribéry, Robben, Manuel Neuer, Phillipp Lamm, Thomas Müller and Bastian Schweinsteger was the ultimate test of any footballing ethos.
Manuel Pellegrini's could be found in the insistence that whoever gets picked in the Manchester City XI his desired style of high tempo, pressing football would not change.
The intent to back your beliefs should be admired. "We can change the names but, for me, it was important to see the same philosophy and the same desire," said Pellegrini before last week's 5-0 Capital One Cup dismantling of Wigan Athletic.
But this was before the Bayern Munich juggernaut arrived to give City a lesson they did not want but may admit one day was required to comprehend what is needed to mix it with the true continental elite.
5 Are Bayern stronger than last season?
Robben and Jérôme Boateng smiled before shrugging the question off when it was put to them in the pre-game media briefing. The evidence suggested that Guardiola has done what sceptics thought was impossible following last season's European Cup, German Cup and Bundesliga treble under Jupp Heynckes: made Bayern even better.
From the moment Ribéry collected the ball on his left flank, cut inside, and let go a rocket that proved too hard for Joe Hart, scored, Bayern announced they were going for the jugular.
Seasoned observers struggled to find an example of City being humiliated like this in recent years and the truth was this was as bad as when Germany took England apart at the 2010 World Cup in Bloemfontein when recording a 4-1 win.