What If... Captain Carter Were the First Avenger? - S1-E1
Factual error: When Stark starts telling about the Tesseract, the colonel shows surprise that Nazis were in Norway. Peggy answers with "Close. HYDRA." The scene is set in 1943, and Norway had been occupied by Nazi Germany for three years already. Them being in Tønsberg should not come as a great surprise to an Allied commander. (00:07:10)
Suggested correction: I feel like this falls under the "Not a mistake because it's an alternate universe" umbrella. We're in an entirely different universe with a different timeline in this episode.
The show also makes a point that the only difference should be the minor choices or events befalling the MCU characters, and how these minor things have huge consequences for them, basically creating a new alternate timeline. Basic world history before these events is not affected by the new timeline.
Basic, unaltered world history does not apply with this because we are talking about an alternate WWII from the beginning. One with Schmitt/Red Skull as propaganda minister of Hitler, Hydra superseding the SS, super soldier serum, Stark tech, the Tesseract, etc. It is not WWII as we know it, even without the "what if."
What If... Captain Carter Were the First Avenger? - S1-E1
Deliberate mistake: When Peggy and Steve are studying the map where the 107th Army division is held captive, the names on the map are nonsensical names that do not even follow German spelling or standards for place names ("Farfignugen," "Dädtenorth," and "Rosskjhberg," for instance). Most of them are also reused, appearing several times on the same map. This is most likely done deliberately so as to avoid any resemblance to real places, but still looks out of place and illogical. (00:11:27)
What If... Captain Carter Were the First Avenger? - S1-E1
Other mistake: The premise of the first episode is flawed; "a single choice" should make the difference, the choice being identified as Ms. Carter not leaving the room to get in the observation booth. But in the normal timeline the booth is exactly where all the other characters were. In this reality everyone else is downstairs, with the German spy that inexplicably sets the bomb early. If anything, it's his bizarre, suicidal choice that matters.
Suggested correction: Except it was her decision to not leave the room that delayed the procedure and gave Heinz Kruger the chance to attack. And with her in the room, she is now given the chance to volunteer to take the serum.
How did her staying delay the procedure? Besides, in OTL the spy only triggered the bomb after he saw the procedure succeed, to know it works before stealing it.
What If... Captain Carter Were the First Avenger? - S1-E1
Factual error: In the intro, we are shown how Nazi Germany spreads across Europe - but after showing Denmark being conquered, it is shown to start spreading across Sweden. Sweden was never occupied by the Germans in WWII.
Suggested correction: I feel like this falls under the "Not a mistake because it's an alternate universe" umbrella. We're in an entirely different universe with a different timeline in this episode.
The show also makes a point that the only difference should be the minor choices or events befalling the MCU characters, and how these minor things have huge consequences for them, basically creating a new, alternate timeline. Basic world history before these events is not affected by the new timeline.
Suggested correction: The black spot spreading is not representing territory physically conquered by the Nazis, but more of their sphere of influence expanding. It is a steady spread and not a true representation of the war's progression. You can notice how Switzerland is also covered by the black, even though it was neutral during the war. Nor was Italy conquered, but their ally instead.
What If... Doctor Strange Lost His Heart Instead of His Hands? - S1-E4
Plot hole: The episode has wonderful writing from a pure storytelling perspective, however it has zero coherence with the MCU it is supposedly part of. The show was written way before "Loki", for instance, and concepts like "Absolute points" are at odds with it. Likewise, Strange and the Ancient One's powers are radically different (Strange can't foresee the future but can go back at will without rewinding and his mentor can seemingly see past her own death).
Other mistake: Dialogue when the heroes locate the base; "The beacon's location was corrupted in transit, we have no idea where it came from." "Well, it looks to me your message is in non-linear hexacode" "That location looks familiar, Agent Carter?" And Sharon instantly identifies it. It may make sense when you write it, but not when there's no pause between sentences and no 'location' is shown. From "We have no idea where it comes from" to "Does it *look* familiar?" through a non-sequitur. (00:08:00)
Other mistake: Supposedly the one difference between this universe and the movie canon is that Janet was infected by a zombie virus before she was saved by Hank and Scott. However, in the original movie Janet actively led them to her by 'possessing' Scott and while intelligent, these Marvel zombies can't communicate. Also, Vision is settled in Camp Leigh, which appears to be in perfect shape despite being hit by a missile powerful enough to penetrate in the bunker in Winter Soldier.
Suggested correction: As I said in my other correction, differences between the MCU movies and this show cannot count as mistakes, since they are showing us different universes with different outcomes. Just because Janet lead Scott to them in the movie doesn't mean that's what happened in the show's universe. Same with the "Winter Soldier" discrepancy.
Without Janet leading them, they wouldn't have even learned about her existence based on what was shown in Antman and The Wasp, and they show the laboratory scene pan out as it did in the movie. Althought technically she could have been infected by the zombie virus in the minutes it took them to get to her inside the Quantum Realm. You realise that it's flimsy and it relies on people essentially not remembering the movie, though.
What If... Ultron Won? - S1-E8
Plot hole: At the end of the previous episode, the Watcher gets surprised (literally saying "wait, what?") by the arrival of Infinity Ultron inside Party Thor's universe.In this episode we find out the story of Ultron.Ultron realises for the first time that there are other universes to conquer right then because he can'hear' the Watcher talk (to whom?) and goes after him.So the two episodes don't match;Ultron couldn't have reached the other universe "before" his realization, and Uatu is again surprised by it.
What If... Ultron Won? - S1-E8
Plot hole: Ultron cuts through Thanos like butter and acquires the Infinity Stones. He does so after he kills all life on the planet (-2). So Thanos has all the Stones (except Vision/Ultron's) years earlier than normal continuity, for no reason. Not just that; Ultron proceeds then to 'silence' the rest of the universe one planet at a time (which would take forever; Thanos wanted the gems exactly to avoid doing that and make genocide efficient). Amongst those planets, one where he fights The Guardians of the Galaxy, including...Gamora, who should be dead or Thanos could have never got the Soul gem.
What If... Ultron Won? - S1-E8
Other mistake: Ultron exterminates the world population quite literally nuking the planet. Black Widow and Hawkeye survive because they are in the air during the global inferno (that's not really how it works) and for the rest of the episode they saunter about on a world full of the deadliest level of radiation in a nuclear winter (electricity and cellular phones work, too).
