A couple more:
When discussing Klingons they've rescued from a damaged freighter in 'Heart of Glory' TNG, Picard says to Riker, "There's more to this than we've been told. Why was the Tarellian ship so far off course?" The ship wasn't Tarellian, it was Talarian! So maybe it's only a small mistake, but it's their fault for picking names of species that are so similar, why didn't they call then something completely different.
This one is better. Troi and Devinoni Ral enjoy an intimate dinner in her quarters in 'The Price' TNG. At one point Ral lifts his fork from his bowl to his mouth with nothing on it, and still takes a bite. Obviously, he hates the food and is just pretending.