Corrected entry: When Max is tied to the steering wheel, he starts hitting the horn with his head and yelling out the window. When you see the cab from behind, the flashers are on. With his hands tied the way they were, there was no way he could've turned the flashers on.
Cynthia Gurski
31st Oct 2018
Correction: There's a chance Max turned the flashers on since he made a stop and was waiting in an alley. They may have already been on just before Max was tied up.