Yeah, there is all sorts of weird interactions riot needs to look at. Like ezreal's E allowing him to still teleport when he's hit with CC because he started casting it before or right as it hit. One of the worst i've seen is when a blitz hits him with his pull, and ezreal teleports and blitz fist goes with him(the long arm chain thing and all) but he isn't pulled. I get how it works, but I still think it's really funky with how certain dashes/teleports work with some spells.
Not even just those though, there's a few i've noticed that are in no way intended. Speaking of Cass, i've actually been turned to stone by her ult when I was facing away from her MULTIPLE times over different games. My whole team and even the enemy team brought it up most of the times it happened, so it wasn't like I saw my character facing away when I tried to bait it but I actually wasn't due to lag or something. When all 10 players see me clearly facing away from her, but it still turns me to stone, there's a problem lol. Also it wasn't like I was at an angle and it just barely caught my vision, it happens when my character couldn't possibly even see cass out of their peripheral vision.
Some of the funky interactions in league can be neat sometimes, but there are definitely some "game breaking" ones that can wind up giving up a kill or losing one that riot needs to look at SOMETIME at least. Some have been in the game since season 1 and haven't been fixed but definitely don't seem intended by tooltips and such.