During a flashback, a teacher informs the class that sodium bicarbonate will react with water to create "lava" for their small scale volcano. In reality, an acid such as vinegar is necessary to cause a reaction, thus causing the sodium bicarbonate to release C02.
In one of Ben's flashbacks to his childhood, his father drinks DHARMA Initiative beer. The cans have wide mouth openings - but this type of can wasn't first manufactured until much more recently.