So I have a 98 civic hatch and everytime it rains, there's always a lil bit of water in the trunk. I already replaced both taillight gaskets. Are there any other known areas that can leak?

 

The easiest way to narrow this down is to do a leak test.

Remove everything from the trunk/hatch area of the vehicle. This means the interior plastics and felt linings and such. The cleaner it is in there for this, the easier it will be to see where the problem is.

Get a flashlight, a cup and a friend. Park the car in the shade, since you have a lot of windows which will let light in and could make it more difficult to see detail (which is why you have the flashlight).

One person get in the car where he/she can see the interior of the trunk/hatch area.

The other person should be outside the car with a cup of water (or a VERY GENTLE flow from the hose).

The person on the outside needs to pour water on the car. BUT! You want to pour the water on the lowest suspected point of a leak. So don't start at the top of the hatch. Start at the taillights, for example. Pour the water on the car and wait a second.

If there's a leak there the person in the car should begin to see the water dripping in.

If that's not eh source of the leak, do it again, but slightly higher.

Do this around the entire seal/taillight/moonroof area (though US hatches shouldn't have a moonroof unless aftermarket). Eventually you will find the source of your leak and you can go on to fix it from there.