You should have sourced this or described the error. It is irresponsible not to do so.
Here is the information which sounds stunnigly trivial to me:
Film historian and archivist Robert Harris has detailed a flaw in the upcoming West Side Story Blu-ray. As his October 25th Home Theater Forum posting indicates, Harris obtained the UK Blu-ray release and noted that what was originally a dissolve transition from designer Saul Bass' skyline pattern to the main title now appears as a fade-to-black/fade-in transition. According to Harris, this mistake occurred in the HD master of the film; it went unnoticed and eventually appeared in the Blu-ray.