1) What happened
If 'list' is a List<Foo>, and list is empty, then list.Sort() will be fine in Unity Editor or WebPlayer (it's effectively a no-op) but export that to Flash and it will RangeError.

2) How can we reproduce it using the example you attached
Repro project attached.
Run in the Editor, observe the expected log.
Export and run in Flash, observer the RangeError in flashlog.txt
NOTE: I'm using an unrelease version of Unity with DXT5 support, but I do not think it's related. Try it in any Unity release.