10 Times The MCU Broke Its Own Rules
4. All-Seeing Heimdall Doesn't See Thanos Coming - Thor: Ragnarok
Asgard's former Bifröst guardian Heimdall (Idris Elba) was known for his all-seeing, all-hearing abilities, capable of presiding over almost anything that happens within the Nine Realms.
Except, uh, he doesn't see Thanos' (Josh Brolin) ship coming at the end of Thor: Ragnarok, leading to the demise of not only himself and Loki, but also countless other Asgardian refugees in Avengers: Infinity War.
There are a few ass-pull possibilities to explain this issue, namely that Thanos had found a way to mask himself from Heimdall's sight, or if you really want to reach, that Heimdall simply wasn't looking in the right place.
But really, this is just another plot-motivated convenience at the end of the day, even if it made Heimdall look like a total dope.