On levels that have a set limit on the amount of blocks you are allowed, you can create infinitely raise the maximum block limit of a block type by placing a block, deleting it, and them just holding the delete key/button. You can also cause the amount of blocks available to become NaN by entering a level, and before placing anything, clicking delete.
This glitch can cause any level which has block limits to be easily exploited and beaten.

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Item duplication has been used here to create a NaN block and 716 blocks.