There is one bridge which is impossible to ride across with your horse.
(But no problem for your character to walk across alone)
The horse can't make another step (jumping doesn't work either)
It is possible to cross the bridge from the "Lovely Point Groves"-side but the horse can't get to the land on the other side due to the invisible barrier.
Same when trying to cross the bridge from the other side - the invisible barrier blocks my horse from stepping on the bridge.