If they were mad before, I can't imagine the monsters are pleased with our antics now. Let's get out of here!
See if you can get the horse moving.
It should be safe to open the latch now; that'll put you behind the horse.
See if there's anything useful within grabbing distance of this spot.
1 - Anything that's keeping the cart itself from moving. 2 - Something to give the horse motivation to move.
Anything heavy in its way, or keeping its wheels from turning.
It may blend with the environment a bit, so remember that you can press the spacebar to see nearby interactive elements.
The brake in one of the front wheels can be released - that's the first issue dealt with.
A firm whack should do it.
Remember, this is a point-and-click adventure games; your arms won't do it.
The horsewhip next to Geron will do the job - grab it, then use it on the horse.
Finally away from that awful place - but what's waiting for us on the road?