Murdering Thanos in the beginning

By far the most interesting part of the film was the way that the Avengers hunted down a weakened Thanos, who was living a simple, pacifist lifestyle on a remote farm.

Not only do they ambush him and cut off his arm (fair enough, considering how destructive he’d been in the past), but Thor executes him while he is clearly crippled, weakened, offering no resistance and no real threat. Not only does he destroy the Stones to remove his own temptation to further change the universe, he also expresses remorse over the way he treated Nebula.

I actually thought the film might explore some lingering guilt the team might feel over basically carrying out a revenge murder on a former opponent who had no interest in fighting back ... particularly Thor, who is probably used to honorable combat as a 1000-year old warrior.

Alas, they didn’t. And it seemed like the film went out of its way to make “past Thanos” cartoonishly psychotic (with a ridiculously big sword) to make the murder of his future self by the “good guys” seem more justified.