Snell suffered multiple injuries in his career, including torn knee cartilage in 1967 and a torn Achilles tendon in 1970. In 1971, he hurt his knee in the preseason and was diagnosed with a severe "knee bruise" and missed nine games. In 1972, in Week 4 versus the Miami Dolphins, he suffered a ruptured spleen. The injury was so severe that his spleen had to be removed, ending his season. He decided right then that he couldn't play anymore, though he didn't formally announce his retirement until the following March. He only played in a total of 12 games in what would be his final three seasons.