minecrat's hit box error

I summoned a minecart with command blocks to make a roller coaster.

but it moved strange, so i turn on the hitbox. so i know what it is strange

It's not just visually like this Really, the hitbox is weird

trigger: set rail. then set commend block on top of 3 blocks. and set /summon minecraft:minecart ~ ~-1 ~(also ~ ~-2 ~)