Continuity mistake: As George says "That you people are rearranging my genes so that everyone will be like everyone else" he puts his left arm around Nick. His hand, though is on the back of the sofa. Instantly in the next shot, however his left hand is now on Nick's left shoulder.
Continuity mistake: Richard Burton returns to his house and cannot get in the front door, because Elizabeth Taylor and George Segal came in, put the inside security chain on the door and went upstairs together. In the next scene, Burton and Sandy Dennis are talking in the front yard. At the end of the scene, Dennis turns and goes into the house. Burton and Segal haven't come downstairs yet, so no-one could have taken the chain off.
Suggested correction: Burton has already kicked in the door prior to this scene.
Continuity mistake: When Martha is on the floor by the coffee table crying as George tells her about their son being killed, she has two lines of tears on her cheek, when the camera pans back she only has one tear that has streamed down.
