In previous versions (1.10?, 1.9?, 1.8), when a Minecart carrying a Mob passed over a powered Activator Rail, the Mob would be ejected onto the square to the left or to the right of the Activator Rail (visualise a flat 3x3 area, a regular Rail and an Activator Rail and a regular Rail forming a straight line, passing through the middle line of squares on the bottom layer of an otherwise empty 3x3x3 cube)

In version 1.11.2, the Mob is now ejected onto the square with the Activator Rail.

Note: if the Minecart is carrying the Player, the Player is (still) ejected to the square to the left or to the right of the Activator Rail.