Or do you have to open the box to find out which version it is.

The FAQ says the 'Revised Printing' tag appears on the rules/manual covers:'If the tag “Revised Printing” appears on their covers, you have a corrected copy and no further action on your part is needed. If such a tag is missing, you have a copy of the initial Forbidden Alchemy shipment.'

Currently there is only one printing of Forbidden Alchemy. The second printing will not be available until some time in February.

When the corrected version is available, you will find the print date by the SKU on the box.