I've noticed that if i was moving around on a sled, with a cart following me, when i go on a frozen lake I speed up dramatically but my cart is left behind. Actually, the cart doesn't even disconnect from me, i can just wait for the cart to get back to me, even if it's more than a screen away.
Not relevant to this particular bug : Carts may disconnect from me for no reason at all (no collision or anything) when moving around on a horse. Doesn't give the usual error message when a cart get blocked by an obstacle. It can be frustrating when you're out hunting and 5 mins later you notice that your cart is no longer following you.