Continuity mistake: When Pinkman and White are having breakfast in the diner, the items on the table keep changing in each shot. Specifically, the jelly, the milk, the cup with the cream and, most noticeably, the rolled napkin with the cutlery inside: Sometimes folded, others opened.
Continuity mistake: In episode 2-10, Walt installed a new gas water heater. The gas lines run from the left wall to heater mounted on the back wall of the utility room. In episode 4-11, Walt is in the crawl space under the utility room. The gas lines are no longer visible.