The first film was weirdly half-assed about his height. There would be scenes shot from the torso-up where Wolverine was much shorter than Cyclops. Then less than a minute later there would be a scene where everyone is walking and Wolverine is clearly quite tall.
A lot of movies are like that, and it's not like the LotR/Hobbit flicks didn't have wildly varying sizes also
Jesus any movie with Tom Cruise
And it's not believable if you're familiar at all with proportions and things like that (Affleck being significantly larger than Cavill for example), but it's an easy thing to not notice
But I'm at the point where I'm like one of those Digital Foundry guys and all I see are the cracks in the clay instead of the pretty pot