場合 is actually quite similar in usage to 時 in some respects, and often used for conditionals (in the case that...). 場合によって is worth learning as a collocation.
状態/状況 - I've seen one description suggest this is the same difference as もの・こと, but they're sometimes tricky to separate. There's some overlap with 様子, too. At any rate, these are both referring to the condition/state of something at one point in time.
事情 - like the above, only includes not just what the situation is but the circumstances that surround/lead up to it.