Other Possible Issues

Here are some things that might go wrong during the program, and how you can handle them.    

Issue: Things just don't work out for a mentor.
Solution: Call for backup. 

Sometimes "life" happens and things don't go according to plan. It is best to come up with a plan at the beginning of the summer to deal with a mentor that suddenly don't have as much free time as he thought he would, or even worse, a mentor that goes missing.

Having additional mentors assigned to each student is a very good idea, and helps with situations where the primary mentor is not available. Google does not have a policy on additional mentors, so this is something that an org admin needs to decide to have—the earlier the better.

Issue: Communication between participants breaks down.
Solution: Stage an intervention

First off, it is important to create a schedule for communication before coding begins. The org admin and mentors should agree on a frequency of communication that is appropriate for communicating with students and each other. This should be at least once per week, because it is very easy to let a few weeks slip by and then realize that the timeline for the project is nearly impossible to follow.

If, in spite of all your best efforts, you have to deal with a communication breakdown, you will need to step in and restart communication yourself. Meet separately with the parties using the most personal medium available, and then make sure they meet with each other. Reestablish a regular schedule of communication, and find a way to monitor it. 

Issue: Submissions from students are duplicated across organizations.
Solution: The deduplication process. 

Deduplication can be a tricky process to navigate. Make sure it is clear to everyone involved what the student's preference is, what your policy on choosing the duplicate students is, and how strongly your org feels about each particular student's proposal.