Experimental said:
So, did the lorry ran over something? oO
Remember about two comics ago when Link got fed up of her and sicked Navi on her? He opened the blue jar and she started screaming at Erin?
IN the comic where the old man is outside, you see her swing about and yell (presumably at Navi) but it is showing you thigns from the outside perspective, where people can't see Navi.
Now inn this comic, she tosses Navi out of the car and assume the lorry HAPPENS to hit a bumb, but the hint i there that Erin killed Navi, or got rid of her.
Considering how bothersome Navi is (or is made out to be, I've never had an issue) I think Navi was a kind of "Personal Demon" for Erin, or all the gaming characters were, and throwing Navi out of the car was her getting rid of her demons... Just a hunch though