There is a button in the top right corner of the screen (/~/) that, when clicked, introduces a glitch into the page. Each click adds another glitch.

Once inside a page, adding ~ to the end of the URL in your browser will reload that same page in a glitched state.

If the page is left inactive, another form of glitch begins to appear on its own. Moving your mouse returns everything to normal.

A separate glitch can be triggered manually by pressing Shift + G on your keyboard, and disabled by pressing Shift + G again.