The rear armrest in the center of the rear seatback can be used (no occupant in the center seat) or placed upright.

WARNING
Never put your hands and fingers around the moving parts of the seat and armrest:
Putting your hands and fingers around the moving parts of the seat and armrest is dangerous as they could get injured.
Split Folding
Head RestraintsMazda 6 Owners Manual: Service warnings
Component Disassembly
Disassembling and reassembling the components of the air bag system
can render the system inoperative, which may result in serious injury or
death in the event of an accident. Do not disassemble any air bag system
components.
Wiring Harness Repair
Incorrec ...
Mazda 6 Owners Manual: Limitations to SRS Air Bag
In severe collisions such as those described previously in "SRS Air Bag Deployment
Criteria", the applicable SRS air bag equipment will deploy. However, in some accidents,
the equipment may not deploy depending on the type of collision and its severity.
Limitations to front/near front collision ...