Keep looking, you might have to crawl in & have someone douse the car with a hose.

1 - taillight gaskets?
2 - weatherstripping around the trunk?
3 - sunroof drain tubes?

4 - this one's strange but it happened to a friend with collision damage...
There's a channel around the trunk opening, just outside the rubber weatherstrip. It acts like a little raingutter to let water flow down towards the bumper. Where they repaired the sheetmetal, that channel had a hole where the water dripped right thru.