The link should help you more than I http://en.m.wikipedia.org/wiki/Ride-along?wasRedirected=true

Ride- along synonyms ride along (v.) drive along, go along, sail along, walk along Ride-along may also refer to merchandise that accompanies a periodical, such as a CD or product sample. A ride-along (or ride-a-long) is an arrangement for a civilian to spend a shift in the passenger seat of a police car, observing the work day of a police officer. http://dictionary.sensagent.com/ride+along/en-en/

Sounds like a line given to someone in order to kidnap them. :P

"ride along"= accompany/come along as well Example: Can I ride along? Sure you can come with me

please provide the whole sentence. "go along (with)" or "ride along (with)" simply mean to ride with, or go with