Console says, "Munchkin is not defined" on Marketo landing page

I've got a guided template (see attached) that I've used to create a landing page. The first time it loads, it tries to submit a hidden form. If the form submit succeeds, the user is shown a pdf in an iframe. If the form submit fails, the form is displayed in a lightbox over the top of the pdf. All of this works fine in Firefox an Chrome on Windows 10. However, when I load the page in Firefox on a Macbook Pro running OS X Yosemite, the console displays a message stating that Munchkin is not defined and the form is always displayed, no matter what (there should be times when it is never displayed because of a successful auto-submit). It surprised me to see a JavaScript error like this since it's a Marketo landing page hosted within our Marketo instance.

I am making use of jQuery to hide validation messages at certain times, and I thought perhaps the issue could be addressed by defining a noConflict instance of jQuery and using it to execute those hide statements, but nothing changed when I tried doing this.

The Marketo instance where I'm having this issue is running the beta munchkin code.

Any suggestions?