This has come up more than a few times (usually with the remote under a couch cushion) which is why I expected this result. However, it occurs to me that it may be possible to build an inexpensive stuck remote locator using a battery, small RF receiver module and an earphone. I'll try to test this when I have some time - I'm not sure the data out line on the receiver will be adequate to drive an earphone. If it is, using it with no antenna (or a small inefficient one) would mean you have to get close to the source so it might help find the remote by getting you within a few feet.