Wood parts should be smooth and splinter-free. And be aware that some metal surfaces, such as slides, can heat up enough on hot, sunny days to burn the skin. Openings that children can get their heads or feet trapped in. Space between slats should be too large for a young child to get his head caught in or too small to fit his feet through. So metal bars, for example, either should be spaced relatively far apart or very close together.
Cargo nets are also an entrapment hazard.
Cables, wires, and ropes that children can trip over. They either should be out of the way of frolicking children or brightly painted so they're easily visible. Likewise, large, sharp rocks and protruding tree roots should be removed. Equipment that is not securely anchored to the ground, including handrails, ladders, and steps. Surfaces that are too hard.