A red exclamation mark appears at the right side to indicate a hazard is approaching. There are three types of hazards.

Cutter
Sawblades that swing from one point to another. At times they will do a full rotation. Because they are slow, if needed you can stop and move carefully.

Pusher
Resemble suits of armor with a small cylindrical pillar on the bottom. If you touch that pillar, your car will get crushed. Wait until it disappears back into the base until trying to pass.

Signals
Acts as a traffic light. The red light will have a countdown number. Once it ends, the red light will turn on. Touching the patterned line below the light will end your run. Wait until it deactivates until passing.