My first MRI I confirmed I have no metal on my body to the technician, but by the time I was inside I suddenly remembered I have metal fillings. I was so stressed by the time the machine turned on, but yeah no problems at all
The machine was already on by the time you were in it. The magnet does not get turned off.
True, but the RF coils do get turned on & off. Heating of non-magnetic metal from the radio waves used for scanning is another concern, not just magnetic force.