If you put around 8+ minecarts on a rail and push them they will go on forever unless hitting an obstruction.

I was messing around with rails and wondered what happened if i spammed minecarts onto a rail, then power them. They went on infinitly so i tried lowering the number until i found how many it was, then tested to see if i could push them, which you can.

I didnt know what would happen, as i said i was just messing around

1: Place rail
2:Spam minecarts onto it
3:Push
4:Watch it go on forever