One of the safety things I was taught from an early age was that the stirrups should always be the correct size for the foot, two finger width between the side of the foot and the stirrup side.
With English stirrups the leather should break free from the saddle, the stirrup leather bars are designed to allow this and the clips should not be set up. The other thing is that of you roll onto your stomach the foot breaks free.
My brother was still quite young - I think around 13 or 14 when his foot got stuck. He was dragged about 300m before his boot came of. He still has the scars to show and he is now 32. A LOT of skin came of his arm that day. Posted via Mobile Device
Like Foxhunter said, use the correct sized stirrup.
ALWAYS have a stirrup pad to add friction.
Ride in BOOTS with a heel, never in sneakers.
Ride with ONLY the ball of your foot in the stirrup. NEVER ride "Home."
If you are worried, get a pair of peacock stirrups, that are breakaway.
When I started riding it was with leather soled cowboy boots. The high heel prevented getting hung up. Also the leather will slide. When I rode English again it was a good heel and leather soles. To this day I cannot ride with anything but this type of footwear and it stands my hair on end to see people ride with rubber soled boots with a small heel in a western saddle. BTW as a teen we tested numerous English saddles to see if the leathers would let go, even with the tab down. Only one came free, so it's not something a rider can count on. If one should get hung up, try to flip over and the foot will come free.