The bicycle seatstay or linkage component parts used to connect the seat tube and rear axle dropouts can be incorrectly sized which can cause the frame to collapse, posing a fall hazard to the rider.
The diving hose that connects the regulator to the tank's pressure gauge can separate reducing the available air supply to the diver, posing a drowning hazard.
The front assembly of the kickboards/scooters can break and the handle can detach or partially detach, causing loss of control or loss of balance. This poses a fall hazard to the rider.