Probably intended as “[Did you remember to] turn mirrors in ???”
I’m more interested in why people shouldn’t wash dueling rear wheels and oversized ones. Maybe they’re like cats and spraying them with water will stop all the fighting.
I’m not a car person but I’m assuming they meant to prohibit dual (as in ‘double’) rear wheels as I don’t think there’s a configuration that would warrant using duel (as in ‘fight’).