Actually, there are ways to prove a hidden volume indirectly. For example by the file names you opened or the last modification date of a truecrypt container file. There is an article about all the small things to watch on the Truecrypt website.
>There is an article about all the small things to watch on the Truecrypt website.
There is an article about all the tricky things to watch for. They're not any smaller than any other booleans on your system, and with software like encase, such inconsistencies will be found.