Similarities between Midnight and current episode

The favorite episode from series four of Doctor Who is Midnight, which revolves around the doctor being on a pleasure cruise that goes wrong due to an entity causing paranoia. There are striking similarities between this episode and the current one, leading to a fan theory that the entities in both episodes might be related. The fact that the same writer created both episodes adds weight to this theory, highlighting the conscious interaction with one of the writer's most popular works.