Which of the following events does NOT delay the end of a period?

The event that does not delay the end of a period is when a player is injured. In football, when an injury occurs, the game typically gets paused to attend to the injured player, which may delay the conclusion of a period. The other options, such as no foul occurring, no timing errors happening, and no coach-referee conference taking place, all indicate situations where game actions or events are in order and not preventing the end of a period. Essentially, no player injury means play can continue uninterrupted, allowing the period to conclude as scheduled.