Few things i noticed. If i play as RED and the cart has traveled through those self-slide zones to near last CP, if the BLU touches the cart and pushes it back to the self-slide zone, stops moving it, falls back and then RED starts pushing it, the cart speed doesn't reset but moves faster. Basically the "fast speed" sticks on.
Another thing was that i was in front of the cart, ducked while it slided down and got stuck in it. Only after i was shot by demoman, i got off from it. Other than that, i have nothing other to mention.