Sorry; I must've missed that one.
then and than
Than is always used with some sort of comparison—"he's taller than her," "I'd rather see this movie than that one," and so on. Then is often used with some sort of time reference, but it can also be used as an interjection ("Well then!") or as a conjunction paired with if ("If we see this movie, then we can't see that one"). I think that pretty much covers it.