It largely depends on what sort of RAID set it is. Certain versions of Linux MD (software RAID) put the superblock at the end of the RAID device, making it easy for the OS to see the original filesystem and mount it. Others don't. Hardware RAID has similar fun games to play. At least being a RAID1 member it's not (or at least shouldn't be) striped or otherwise mutilated, mangled, or spindled.
Honestly, I'd just make a dummy array (it takes all of about 10 seconds with
mdadm) and mount that. You can derp around with mount options and things, but it really isn't worth it.
(Sidenote: "complains that it's part of an array" isn't a good description of the problem; the exact error message would be far more useful)