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)
An Affair to Dismember - S1-E8
Deliberate mistake: Right after the credits, we see an establishing shot of the mayor's house but it's a reused shot from episode four from when Jake and Lexy snuck inside, just without the digitally added smoke. What gives it away? The fact you can see Jake and Lexy at the bottom corner sneaking in, wearing the clothes they wore in episode four, even though they're already inside and wearing different clothes.