WARNING: The following contains spoilers for What If...? Season 1, Episode 7, "What If... Thor Were an Only Child?," streaming now on Disney+.
In the Marvel Cinematic Universe, fans haven't quite gotten clarification on a major plot hole derived from Captain Marvel. At the end of that film, she left a beeper for Nick Fury to call her in case she was needed, but audiences didn't see him using it until he was being dusted by Thanos. There's been nothing but speculation on this since, and now, it's once more brought into question thanks to "What If... Thor Were an Only Child?"
In Avengers: Infinity War, Fury summoned Captain Marvel before he was dusted, and Carol appeared afterward, ready to answer the call with Earth's Mightiest Heroes, kickstarting the events of Avengers: Endgame. However, it's never been confirmed if Fury buzzed her before, if she got a call and ignored it, if the signal didn't go through or if she was too busy on galactic adventures beforehand.
The latter may have indeed kept a mindful Fury from disturbing her cosmic journey, but with the likes of the Chitauri and Loki wreaking havoc, Ultron's robots going berserk and Thanos' forces invading New York and Wakanda at various intervals, Fury should have hailed her before. Given that the Avengers were overwhelmed or split, it'd have made perfect sense. Instead, it feels like plot convenience where the MCU's just trying to fit her in after her movie was turned into a pre-Iron Man flick.
What brings this dilemma to light is how Maria Hill acts on the beacon after Nick Fury's injured by Korg when Thor brings the party to Midgard. There are no Avengers around, so Hill, as acting Director of SHIELD, needs a heavy-hitter and uses the beeper to call Carol. In the blink of an eye, Captain Marvel appears, ready to throw down and teach the Odinson a lesson.
This feels a tad trivial, as Thor's cool and could be persuaded to chat about his frat dude antics, especially with Jane being on his good side. Regardless, her appearing to defuse the threat once more has fans asking why Fury or Hill didn't bring her over in the main universe for the previous battles against the Chitauri, Loki, Ultron and Black Order, as they all fit the bill as folks she'd need to take out to save the place she called home. Hopefully, clarity is provided at some time on her being used as a deus ex machina, as her summoning is consistent and requires minor groundwork to explain why she was absent when Earth was on the line so many times in the mainstream movies.
A new episode of What If...? airs each Wednesday on Disney+.