It was an in-engine opening cutscene which was very nearly final; the file we shipped was about two or three weeks out of date compared against the version that should have gone on the disc (It had one missing shape key on a character's face at the end of a shot, and a couple other missing elements). My code was wrangling the whole animation; doing all the stuff which our at-the-time-primitive animation system couldn't do itself (animating texture coordinates and etc). And my code was just silently handling all the errors it ran into so that we never even noticed that anything was wrong.
The difference was subtle enough that in the twelve years since the game was released, nobody but the original animator has ever noticed and mentioned it to me (and that, years after release). But that one experience and knowing how much worse it could have been was enough to convince me that "crashes early and crashes loudly with as much detail as possible" is by far the better strategy. At least for entertainment products. And doubly so for entertainment products which can't be patched after release.
(for clarity, this screw-up was 100% my fault. The animators had made the final changes to the cutscene data files in plenty of time for inclusion in the final build, I just somehow didn't import the changed data files into the game when I made the matching changes to the code side, and then my code didn't throw any errors to tell me or anyone else on the project that anything was wrong.)