Seriously Andrew? You need us to help you compile a list? Every component that is involved with keeping you mast vertical is also subject to failure. I've had (or seen others have) the following items break:

Bow tang
Wires
Clevis pins / ring dings
Through-hull anchors

Other than the mast hounds, that's all there is keeping a H16 mast vertical. So, I'd say it's ALL subject to failure. Each boat model will have its own list, since the components are slightly different, but the basic idea is, if it's a part that's involved in holding up the mast, expect that it will fail at some point and should be routinely inspected.

Mike