This isn’t your average day at the races. Camels, ostriches and zebras will invade Sunday at Remington Park, 1 Remington Place, for the fourth annual Extreme Racing event, starting at 1:30 p.m. In addition, the day features a 21-inch miniature horse and pig races on the plaza — oh, and normal-size horsies, too, for your betting pleasure. Admission is free. Call 424-1000 or visit remingtonpark.com.