1 - On a high-tech portal machine. Well, high-tech might be strong. Basically, I'm thinking something that looks like the circular part of a Stargate machine (please note, I've never watched the show) - it can be more hastily made, oblong, or whatever you'd like. The important thing is that the portal portion should be silvery and sheeny (almost certain that's a word) in a manner similar to the element of mercury. If you deem it appropriate, Patrick (who will get more facetime next panel) can be off to the side here, looking at the portal, but the portal should be the focus.
CAPTION (PATRICK) (1): There are infinite worlds beyond our own.
CAPTION (PATRICK) (2): Ergo, there must be some where I didn't screw everything up.
CAPTION (PATRICK) (3): Thankfully, I only need to find one.
2 - Patrick stands in front of the portal, preparing to walk through it. He wears a lab coat, a five o'clock shadow (that's potentially onto 6 or 7 o'clock), and is generally not super kempt.
PATRICK: Here goes--
3 - A man who looks identical to Patrick (save for the fact that he wears a traditional mirror-universe mustache - let's call him Mirror Patrick) stumbles out of the portal and right into Patrick, taking him out with a pseudo-shoulder tackle to the gut. Patrick is taken completely by surprise by Mirror Patrick's unexpected appearance.
MIRROR PATRICK: -- nothing!
4 - Patrick and Mirror Patrick lie tangled on the ground, both trying to shake off the cobwebs of the sudden impact.
5 - The Patricks make eye contact, realizing what has happened. They wear identical expressions of frustration / annoyance.
LETTERING NOTE: Have Patrick and Mirror Patrick share a word balloon as they speak the same words at the same time.
PATRICK & MIRROR PATRICK: What are you doing?! This is my idea!