Theft and Damages

I sent a mud cake as a practical joke for Mishloach Manot to my best friend, and the cake made its way to the wrong person. Do I have to pay for the damage?

The man who sent a mud cake for mishloach manot and the cake made its way to...

My friend picked up a trempist (hitchhiker) who did not put on his seatbelt. Police pulled the car over and gave a ticket to the driver (not the passenger) for driving with someone not buckled. Should the passenger reimburse my friend?

If I mistakenly caused a very minor scratch on a car what does the Halacha require?