This morning I was reading newspaper and came across this article "Robot Kitty event staff lodge reports over unpaid salaries".
The Robot Kitty Singapore exhibition was held last month and at least 70 of those contract workers did not receive their salary. The founder is currently uncontactable. Those workers are currently in a bind due to the agreement was "contract for service", not "contract of service". "Contract for service" are independent contractors, which are not covered by Employment Act and statutory benefits do no apply.
I guess everyone have to be really careful before signing a contract.