To piggy back off this post, cart seems to be bugged for multiple interactions. After sciencing in the atrium with a friend we believe that if you get hit by the cart then you are considered in the cart regardless if you actually are. That means that when the cart ends, either by hitting something or because it went through the doormans door then it will teleport you to the cart or at least where the cart was in the case of the doornmans door. It also applies the stun too even if you use an ability to avoid it.
Item interactions tested:
Unstoppable:
Cart hits nothing: Damage, no movement
Cart hits wall: Damage, no stun, no movement
Unstoppable (Expires before cart hits wall):
Cart hits nothing: Damage, no movement
Cart hits wall: Damage, stun, no movement
Counterspell:
Cart hits nothing: Damage, no stun, no movement
Cart hits wall: Damage, stun, no movement
Ethereal Shift:
Cart hits nothing: No damage, no movement
Cart hits wall: No damage, no stun, no movement
Ethereal Shift (Expires before cart hits wall):
Cart hits nothing: No damage, no movement
Cart hits wall: No damage, stun, no movement
Rescue Beam an Ally out of the Cart:
Cart hits nothing: Damage, pulled towards ally initially, then rubber bands to cart end
Cart hits wall: Damage, stun, pulled towards ally
Divine Barrier:
Cart hits nothing: Damage, freed from cart
Cart hits wall: Damage, stun, freed from cart
In additional all of these interactions, if the cart goes through the Doorman's door then the hero is teleported to the doorway. We assume this is because as mentioned before anyone hit by the cart, even if they are immune in someway, is still counted as being in the cart when it is teleported to the exit door. This can create some truly wacky rubber banding in the case of things like Rescue Beam where you are pulled to the user only to be teleported half way around the map to where the cart actually ends.
Hero Interactions:
Infernus using Flame Dash:
Doorman's perspective. Moves in the direction of the cart slower than the cart itself until the cart stops
Infernus' perspective: Rubberbanding
Calico using Leaping Slash:
Doorman's perspective: Is stopped pretty much in place +/- 1m
Calico's perspecitve: Rubberbanding
Paradox using Ult:
Doorman's perspective: Dragged in cart direction
Paradox's perspective: Rubberbanded to cart location
We suspect that all movement abilities/forced movement will end up being the same situation and we also tested the above interaction and replicated dragging someone out of the Baroness and forced max damage on them. Also the reason we believe this is a bug is because Reactive Barrier will trigger when you are hit by the cart because you are movement locked. But if you unstoppable and are hit by the cart you are not movement locked and it doesn't trigger. In that case you shouldn't be teleported either as that would probably count as forced movement and a movement lock
If it does end up being that people are still registed as in the cart the second they are hit then we recommend changing it to accurately track when people are and aren't in the cart. Unless everything is working as you intend in which case: good job?