Answer: Pronoun reference.
Explanation: A pronoun is a word used to substitute of take the place of a noun. When using a pronoun, we need to have perfectly clear which is the noun that the pronoun is substituting. When this isn't clear, and the pronoun can be referring to two or more nouns, we have a problem in pronoun reference. That is the case of the given sentence. When it says: "It ended in a tie" the pronoun "it" can be replacing "The crowd" or "soccer" so in order to make the sentence clear, we can rewrite it like: The crowd sat through two hours of rainy soccer, which ended in a tie.
