Prerelease information refers to information about video games and related media prior to the release candidate. Prerelease information may be gathered from a number of sources including magazines, developer interviews, advertisements and early game footage.
Something similar to prerelease information is unused content. Unused content refers to things found in a game's code that are not used in normal gameplay. Examples may include unused images and models, music, text (usually development or gameplay related) or unused game mechanics. These give insight about the development of the game even if some of the content was not intended to be added to the final game from an earlier date.
'Beta' is sometimes used as a blanket term for prerelease information and unused content, but the term is less objective.
Magazine extract, saying that a 'skateboard' in Pokémon Gold and Silver
will allow access to 'unexpected locations'.