In Extreme mode, the passage to the Basement is blocked off by an iron gate. The iron gate will no longer appear in its usual position leaning against the pole holding up the Basement. However, it is still possible to go into the passage from this side.
It is actually possible to throw specific items behind the Iron Bars, these items include the following: Battery, both Cogwheels, bothVases (glitch), Freeze Trap (glitch), Spark Plug, Remote Control, Padlock Code, 2 of the 3 Shotgun Parts (Buttstock and Trigger), and the Note. Additionally, any key can fit through the iron gate but its hard or impossible to get them through because of how they are thrown. The Barrel of the Shotgun can also make noise on the other side from the tip of it, this is hard to do however.