I think it referred to its impulse rather than momentum, aka v*m. The cartoon might be a bit flawed though, as the car is stationary (or at least we can assume it is) relative to the spectator, so the impulse would be 0 and mass irrelevant. PS: Not a quantumphysicist, not even a normal physicist or even remotely related to the field.
I don’t mean to imply anything, but this post was listed maybe one scroll away from the piracy community welcoming everyone to SimpleX. Unfortunate timing.