When Margo is alone with Matt, and Matt starts to spasm, she is wearing glasses. The next shot shows her outside the room calling a nurse, without glasses. When she is in the room again, the glasses are back on.
When Chase and Cameron check the bus for poison, it says "Plainsboro Unified School District" on the side. New Jersey does not have Unified School Districts. Plainsboro High is part of the West Windsor-Plainsboro Regional School District (which is what it actually says on the buses). Unified School Districts are used in only a handful of states - including California, where most of the exterior shots were filmed.
Foreman explains one of his professors at Columbia had developed targeted agents to counteract pesticide poisoning. It was later established Foreman had gone to Johns Hopkins for both undergrad and med school.