When you come across one of the infamous "push column mazes" or any columns you think could obscure a secret area, use the following this trick to check which columns move. Activate Shrooms Mode Power-Down by enabling the badtrip code, or find a Shrooms Mode pick-up. After that, look at the column you want to check. If you can move the column, or it moves in any way, the column will flash all sorts of strange colors. If the column does not move, it will remain the same as in normal mode. Be careful before attempting this, as Shrooms Mode makes the game very difficult to play. Make sure the area is secure before using this trick.
Wait for one of the demos to begin. While the demo is playing, press F6 to quick save. Go to the main menu, and load that quicksave file. You will have "warped" into the exact scenario in the demo, level and all.