Non-Canon

''So... a mortar?''

Any official information that doesn't count towards the core facts in a franchise's universe is considered non-canon. This could be an event in the future, a dream, or a story one person is telling another. An event or character that is part of the non-canon is non-canonical. With non-canon, the creators could get away with showing something that is impossible or doesn't actually happen as it doesn't affect the overarching lore.

What counts towards being canon and not could be confusing in episodic TV shows as characters do not reflect on past episodes other than in two-parters, Self-Referencing moments, for Nostalgic Catering, or to make a quick joke.