“The explanation behind it: they were having a ride on Dash’s moto scooter nothing to do with the new movie when they had an accident, and Dash used her own body to protect Twilight, so she’s the one who got the worst injures, and now Twi feels guilty for that, even tough Dash keeps telling her that if that would happen again, she wouldn’t doubt to do it again, just for her.
About their hair, well, they both got it burned out after the scooter exploded, and Rarity decided to fix it for them both “