10 Times The MCU Broke Its Own Rules
2. The Scarcity Of Pym Particles - Avengers: Endgame
When the Avengers first mount their "Time Heist" in Avengers: Endgame, Ant-Man (Paul Rudd) makes it abundantly clear that the team only has a limited number of Pym Particles left.
And while we do see 2014 Thanos being given a Pym Particle by 2014 Nebula (Karen Gillan) in order to travel to 2023 and battle the Avengers, it's never explained how the rest of the Mad Titan's army, clearly numbering in the many thousands, are able to join him.
However, Endgame co-director Joe Russo explained away the inconsistency in an interview by claiming that Thanos' acolyte Ebony Maw (Tom Vaughan-Lawlor) simply used his magic abilities to reverse-engineer new Pym Particles from the one given to Thanos.
But given that Russo's explanation is both rather contrived and not actually given to the audience in the movie itself, it can't help but seem like another ass-pull.