The lead villain, Pierre, is consistently drawn with his right ear enlarged and distorted. His left ear is drawn with normal proportions. This could mean that Pierre has what is known as a "Cauliflower Ear". This is a common injury among boxers and fighters and could imply that Pierre has been a fighter of some sort in the past.
The truck that Dr. Quest took into the woods appears to be a Corvair Rampside pickup.