It should have a placard on the front of the basket or the back of the seat that gives the company you rented from and the last name of the person who did the rental. However, if there are several
ECVs parked together, trying to find yours by that is like trying to pick out your car by the license plate in a parking lot. It's possible, but slow and cumbersome. If you leave your
ECV in stoller parking while you walk into a store, or if a ride has an unload spot different from the loading spot, the CMs may move the ECV, so you need a way to quickly pick it out.
Some people tie a distinctive scarf on an arm or on the basket. I have a brightly printed tote that I leave in my basket. I do not leave anything valuable in the tote -- my money, camera, cell phone and KTTW all go in a waist pack that stays with me. But the tote has things like my fan, a bottle of water, park maps, etc. Stuff that is helpful to have but won't break my heart if it "walks off". Mind, nothing ever has disappeared from my basket, but one never knows.
Depending on how high it sticks up, the bike flag could give you problems or buses or monorails, or in shows. I did wish I had one last time when a friend and I went together, both on ECVs, as it would have helped us stay together.