I'm creating a database of "books". Each book is made up of EPS files stored in a repeating container field called "Pages" I have a calculation returning a container called "PageView" and a third field called "CurrentPage" The calculation for pageview goes like this:

Pages[CurrentPage]

This works like you'd expect. Enter a page number into CurrentPage and PageView returns the EPS data stored in that repetition of Pages. The script I use to get the EPS files into the repeating fields stores them as pictures.

My problem is that some EPS files will display their contents in the container field (the desired behavior) and some will simply display an icon and file name as if I had stored the data as file rather than as picture. Is FileMaker's ability to display EPS in container fields limited in some way?

I think that the EPS files that are displaying in the container field are likely showing a PICT or TIFF preview image, not the EPS graphic itself.

I believe so too: it seems only a file with a PICT preview will be shown on a Mac (might be different on Windows?).