In Star Trek Enterprise, there’s an episode where the crew finds a planet being ravaged by disease. Bizarrely, the planet has two humanoid species: one dominant (intelligent, technologically advanced) and one less dominant (less evolved brains). The captain mentions that in every planet they’ve encountered, only one humanoid species survives the process of evolution.

Well, it turns out that the disease is genetic, it only affects the currently-dominant species, and they will go extinct in a few centuries because of it. The same evolutionary phenomenon that explorers encountered countless times before on other planets was happening right before their eyes.

Middle Earth has like at least 3 humanoid species (Man, Elf, Dwarf), more if you count Hobbits and Orcs. That’s totally incompatible with Star Trek lore!