Sure. Take one mathematical fact which the mathematical community accepts as true, but which has a complicated proof only recently published and checked. Surely your epistemic probability that there is a mistake in the proof and the theorem is false should be larger than the epistemic probability of the Gladstone story (if you are not convinced, add more outrageous details to it, like Gladstone telling the Queen "What's up, Vic?"). But according to your current beliefs, in the actual world the theorem is necessarily true and its negation impossible, while the Gladstone story is possible in the MWI sense.