When a spash potion lands on a block, the particles always come from the north-west corner of the block. This happens in a ton of versions, going all the way back to 1.8.1 and possibly earlier, but for some reson the bug tracker won't let me add them.
MC-102307
Splash potion particles appear in the wrong place
Resolved
Duplicate
0
Luke W
(Unassigned)
Unconfirmed
Minecraft 1.9.2, Minecraft 1.9.3, Minecraft 1.9.4, Minecraft 16w20a
Retrieved
This issue is a duplicate of MC-45749. Please search before reporting issues (if you haven't already) to see if your bug has been reported before.