The ”Filing bugs when off-line” section of the bug reporting community help can be applied here:

First, on the target system, gather the information in a file:

1. For a bug report about a system crash:apport-cli -p <package name> --save bug.crash
2. For a bug report about any other issue:apport-cli -f -p <package name> --save bug.apport

You will need to answer a few questions, which will vary depending on which package the bug report is about. Relevant system information, including the package name, is then saved on the target system, in the current directory. The extension indicates if it is a crash report or another kind of report. If you decide to rename the report file, please keep the .apport or .crashextension.

When the file is ready, copy it to the system you intend to use for filing the report. There you can then file the report:

ubuntu-bug -c <apport_file.extension>