Can you get a possible detached retina from being hit in the head?

Yes: Traumatic tears, dialyses, retinal detachments are possible, also could be higher risk due to underlying retinal predisposing factors such as thinning or degenerations.

Yes: Direct blunt force to the eye or force applied to the head can cause a retinal detachment.

Trauma: Yes, depending of the severity of a trauma to the head, it can lead to a retinal tear and detachment.