I agree. The S hook could definitely be an issue. Also, the link up top could be as well, if your bird is one of those who is more mechanically inclined. Tightening the link with a pliers would help in that capacity, though.
And another potential danger is the bell clapper. There have been quite a few incidents of parrots pulling clappers free from that type of bell and subsequently choking on them. Personally, unless the toy has the cylindrical style bell where my birds can't reach the clapper, I just remove the clappers entirely. They love the sound, of course, but I just don't take the risk.