Based on the images in Armies of the Macedonian and Punic Wars, the helmets appear to be incorrect. I can't tell for sure, but it appears that the helmets of the Principes have eagles on the top. Only the helmets of the Princepes and Equites Alares appear to be correct. The cavalry should have a vexillum instead of an imperial infantry signum. The infantry command has an imperial eagle with a vexillum attached (which was not done) instead of one of the five animal standards of the republic. Some of the shields are early imperial shields instead of the ovals of the republic.
As Jjona pointed out those are feathers on the other helmets. However, the shape of the helmets is wrong.