Read-only caches will contain invalid data whenever the master copy of data held in the back-end array is rolled back in time or restored to an earlier array-based snapshot.
Have one person in charge of the master copy of something, and others propose changes (i.e., pull requests) where each contribution gets tracked and conflicts get resolved.
Part of the plot revolves around retrieving the missing master copy of a film cartridge that makes viewers lose all interest in anything other than viewing it.