The Catholic Church does, in fact, teach that other Christian have access to the Truth and that there can be salvation outside the Catholic Church. The Church, however, believes that the Catholic Tradition has a "Fullness of Truth" that is not present outside of the Catholic Church. That is not the same as the "no salvation outside the Church" statement.
Mel is from a more conservative sect of the Catholic Church
I hope that this clear up the matter for you.
Someone is demonstrating ignorance and prejudice, but it's not Mel Gibson. JPII's book is not a statement of Catholic doctrine. Nor can a dogma change. If it was ever dogma at any time, then it must remain so for all eternity. Truth is not dependent on the decade or the century.