I wasn’t aware of this tiny little thing - the filesystem in the file created by a Wubi install can be easily mounted as a loop device.
To do so, just open the Terminal and type the below:
This will make the kernel auto detect the filesystem type and try to mount it. Alternatively, if you’re sure of the filesystem type, mention it explicitly
Would come in very handy if someone were to migrate from Wubi install to a full install, just copy over the /home files and all files saved.