In one scene where Black Bolt and Medusa are talking, her hair swaps from all behind her shoulders to some over her shoulders several times.
In one scene in downtown Honolulu, Black Bolt looks up high into the sky and sees the full Moon. This would be impossible during midday as the Moon only appears to be full when the Sun and the Moon are on opposite sides of the Earth.
When Maximus shaved Medusa's hair, there was no guard on the clippers, which should've taken her hair down to the skin, yet left her hair half an inch long. It was also uniformly shaved, and it's doubtful he would've taken the time to do so.
In the initial reveal of the City of Attilan within a bubble on the Moon, the direction of the sunlight hitting the Earth in the background is different from that striking the Moon. Given the direction the sun light is hitting the Earth, the surface of this portion of the Moon should be in shadow.
The direction of the light source within the bubble is also different to that outside the bubble but that may be due to some artificial light source.
Gorgon advises his would-be killers that they "should never approach downwind". In fact, downwind is exactly where a hunter should approach if they don't want to be smelled by their prey. He should have advised then not to approach upwind.