I think for games that are several years old, spoilers being in a trivia game are pretty much a guarantee.
For example, questions like "In Half-Life 2: Episode 2, who died at the end?" or "In Until Dawn, it was revealed that..." are valid trivia questions.
Granted, they are spoilers, but they are still trivia questions. They are facts about the game that won't change.
It's not an intentional thing to be spoiled by a trivia question, but it's going to be real difficult to fix this problem. They are trivia questions about the subject matter, and you need to know the subject matter (generally) to answer the trivia question.