Anything that isn't food, super small, or able to be broken down in its stomach it could cause an impaction. If it was enough to be seen in his mouth maybe consider switching out vines / sticks.
If you have a Veiled Chameleon you need to be more cautious of the plants that you do use. They will eat them. Typically those with Veileds stick with pothos and dwarf umbrella trees for live plants. There are others like hibiscus as well but this needs bright lighting. Also you need to cover the dirt with 1 inch are larger river rock so they do not eat the dirt in the pots.