So, you’ve created an awesome Live USB Linux stick with a persistence file which let’s you boot anywhere and carry all your sweet sweet datas around on it too. If you want to see those files in Linux on your desktop or laptop outside the USB you’re going to have to mount the loop device (the casper-rw file) somewhere first. The following commands show how to make a folder and mount the loop and then unmount it too.
Just change the /media/USB/ for the mounted location of your mounted USB stick which contains the casper-rw file you want to view the contents of and the /home/alex/caspermnt/ for the mount point on your system.
mkdir ~/caspermnt sudo mount -o loop /media/USB/casper-rw /home/alex/caspermnt/
sudo umount ~/caspermnt/
This can be useful for recovering data from a borked Live USB stick or for backing up your files on your computer just to be sure.