Nothing.
Except that employer may not issue FNF statement and cheque, settlement of dues, work experience/service certificate, relieving letter, form 16, PF accumulation reports etc. For this employee can lodge a complaint with o/o Labor Commissioner/wages inspector, RPFC etc, and let the employer face enquiries and penalties.
After all it their funeral and let them handle it.
However it shall be appropriate to submit company property under proper acknowledgment. Even if there are 25 guys there must be some supervisor, so charge and company property can be handed over and an acknowledgment can be issued. In such a company supervisor shall be having the same fate hence each one should help each other. On the last day employee should submit a formal resignation letter (citing the reference of notice of resignation) under acknowledgment.