Images showing in simulator but not on the iPhone device

First thing to check is the case of the strings you're using to refer to the resources. The iPhone is case sensitive, but the simulator is not.

Oops, just seen that you checked the case. Better log all your UIImage creation calls then!

Yes, memory absolutely plays into this. Check your UIImage creation calls and make sure they dont return empty. Also, check to see if youre getting memory warnings in the console window.

The simulator accepts a wider range of image formats. Sometimes you had a specific file type that the device cannot display. Double check the 10 files looking for some difference from the others ones.