Error for apt-get install when running Ubuntu 12.04 on flash drive [closed]

Question

I am running Ubuntu 12.04 on a memory stick courtesy of LiveLinux - http://www.linuxliveusb.com/

So I wanted to install git (sudo apt-get install git) and I've been getting the following error message;

W: Invalid regular expression '\.dpkg......
(more stuff about invalid regular expression)
E: Unable to locate package update

I can't do apt-get anything sudo give me the following;

sudo: parse error in /etc/sudoers near line 0
sudo: no valid sudoers source found, quitting
sudo: unable to initialize policy plugin

I'm pretty clueless here. Any ideas?