Physical Danger
Any time you're doing athletic exercise, you're in danger of injuring yourself. That goes for both practice and game days. Even an overenthusiastic pom-pom thrust can cause serious damage if you're not stretched and well-prepared.
Some of the routines may require cheerleading formations, like pyramids, that could result in injury if performed incorrectly. The higher you are, the farther you fall, so make sure you strike up a good relationship with the team doctor and know exactly where the ice packs are kept.