Continuity mistake: In the department store as Clark is talking with Mary, the lingerie sales lady, his left arm is supporting him on the glass counter as he is standing. The next shot when Rusty approaches, Clark is now bent down with his left arm resting on the counter.
Continuity mistake: When Clark is outside hanging the lights, he staples the sleeve of his shirt, under his wrist, to the eaves of the house. In the next shot, as he is pulling, the shirt is stapled over his wrist. (00:21:50)