Well that sucks man ..... you are missing the large spacer that goes between the mount and frame as well as the nut.
I myself wouldn't ride it like that. You will be overstressing the other front mount and without tools to check the other side first and verify it is in and secure its risky.
If you can get a nut and a bunch of washers to fill in for the spacer it would be alright, but make sure you use enough washers and that you aren't drawing the engine & frame mount together and tweaking anything.
Better safe than sorry, live to ride another day man. Tow it home or take a cab home. Go to your dealer & buy the requisite spacer & lock nut & ask him to overnight for you as a favor with the promise that you will buy something else in future. Or just pay for the overnight fee & get it over with.
Anytime man! Way to get it done. I wouldn't ride it like that anymore until you get the spacer and nut. Also go over all the other engine mount bolts and torque them, I would guess that after the "crash bar" install they might all be a little questionable.