If the tank is glass you might break it, the leaking juice will be a tell tale.
You might damage the connector, bend or break it. If it is bent and that does not bother you no problem. If it is broken it will not work.
If it is a regulated mod you might break the circuitry inside. It no longer lighting up will be your indication.
Other damage like that for anything you drop. After you stop crying get used to the scratches and dents, they give the device character, and vape on.