You can find the Orbot source code here:

• https://gitweb.torproject.org/orbot.git
• git clone https://git.torproject.org/orbot.git

And find bug reports here:

• https://trac.torproject.org/projects/tor/query?status=accepted&status=assigned&status=needs_information&status=needs_review&status=needs_revision&status=new&status=reopened&component=Orbot&group=type&col=id&col=summary&col=component&col=status&col=type&col=priority&col=milestone&col=points&report=14&order=priority