I would assume that the industry itself must store this kind of data somewhere since this is a practical necessity (e.g. people need to be paid residuals,...). There is for instance the Motion Picture Credits Database:
Every year, as part of the Academy Awards process, the Academy gathers
credits from films hoping to qualify for awards. To these credits,
compiled and verified by the film's producer or distributor, we add
credits from other films released in Los Angeles County, using
research materials from the Academy's Margaret Herrick Library.
In addition to personal credits, MPC records index production and
releasing companies, MPAA ratings, running times, Los Angeles release
dates, color, language, source authors and source material, all of
which are searchable.
The credits in the MPC database were originally collected and printed
in the Academy publication Annual Index to Motion Picture Credits. The
Index started in 1934 as the Screen Achievement Records Bulletin, when
the Writers Branch of the Academy began publishing a bulletin of
screen authorship records.
... and the Official Screen Credits for Academy Awards Consideration (same page, I'm not going to copy-paste the entire description).
This page mentions several databases, some are only available to UCB users.