When going outside the world border, you will notice there is an invisible border that's outside the world border, you cannot walk through this border as its a border. But when shooting a trident it can go through the invisible world border but this cannot happen since nothing can go through the invisible border and it should instead hit the border.

How to reproduce

1-Start by teleporting outside the world border using this command 

/tp 29999999 256 29999999

2-Then obtain a trident and shoot the trident against the invisible border.

3-You will realize that the trident can go through the border.

Observations: Trident can go through the invisible border.

Expectations: That cannot happen and it should instead hit the border.

Note: Relates to MC-53602 and does not duplicate because it talks about the inside of the world border.