When Maeve first enters the Mariposa Saloon, she looks around and slams the lid shut on the player-piano to stop it playing. In the next scene, the lid is open again.
The first scene when Bernard is talking to his son, he's holding his son's hand and wearing glasses, then they cut to a different angle and his glasses are off.
When Bernard is interviewing Hector, who is naked, a tan mark can be seen on the host. The mark, which has the shape of a swimwear, should not exist, since Hector's character is always fully dressed under the sun in Westworld.
When Theresa is talking to Charlotte in her bedroom, Charlotte asks Theresa if she can bum a cigarette. As Charlotte puts the cigarette in her mouth, it's visible that the filter is facing outwards instead of in her mouth like it should be.