fall through the floor
Version 0.1.1 - Windows 7 64 - Firefox 13.0.1
You can fall through some brick floors by pressing repeteadly and randomly "left", "down" "right" and "jump". I managed to get from the starting position to the subway by glitch-falling :) And also "under" the map.
Though it's rare to press that much buttons, this could happen during some fights with NPCs.
screenshot : http://tiny.cc/mznnhw
François Kmetty commented
Same thing happens when you find a small space where you can go only by move+crouch, which will allow the character to crouch into spall spaces where you can't go normally, then trying to stand up :
If you can't move+crouch, the character should stop to "slide" when pressing "down" to crouch.