I absolutely think you could decorate it in such a way that, if someone hasn't actually seen "Tangled," he/she wouldn't even know that "Tangled" was your theme.
And I think a Tangled inspired bedroom could actually be very romantic!
Use colors inspired by the movie, some really posh bedding, lantern lamps, some abstract "Tangled" artwork, & a gold sun mirror to hang above the bed.
Also, for fun, you could get a cast iron frying pan to use as a "tray" for perfume or something on your dresser!