I recently replaced the right indicator bracket on my EF because somehow the cover popped out and I've noticed a lot of EFs with the right indicator cover missing which I still haven't figured out why but ever since I replaced it I'm having trouble getting it to sit flush with the panel and create a seal and the bloody thing keeps filling up with water, anyone know how they're supposed to be installed properly so they are water tight?

use silicon!

mine where the same. there are 2 little screws with round heads on the indicator that slot into the holder. them unscrew them and put them in a vice and slightly bend them about 15-20 degrees, now screw them in a position that pushes the indicator towards the body. you'll figure it out remember the screws have to have a slight bend in them pushing them towards the body of the car.