Voltron spaceships crashed down from the heavens during the Tourist's destruction of Redacted Pinorva's reality, part of the 10,000 Drafts.
According to the Tourist, the reason Redacted's reality had remained unfinished was that its creator had gotten bored and preferred to write ”space adventures about the Roc's Feather and its crew's battles against the Voltron”. This revelation had outraged Uncle, who claimed that they were nothing compared to the Aubrite he had faced himself, calling the Voltrons “B-movie villains at best”. (PROSE: Breaking the Narrative)