Miranda Violation?

I am a college student, and last night two of the friends that I was with were arrested for pariphinalia charges. Specifically,each of them claimed to ownership of a marijuana pipe. They were not read thier miranda rights. I and another individual, who was also in the car, witnessed them being handcuffed without any rights being read. However, we were let go before they were actaully placed in the two squad cars. We did not see or hear what could have happened between the handcuffs being put on them and them being put in the cars. We were asked to get into my friends vehicle and prepare to leave. Is there a possibility that this could be cause to get charges dropped? If so,how would that be likely to occur? Also, they each have a bond for $1000. What is a bond? Thank you for any information you can provide for me.