The penalties for actions which you might find over the top are taken very seriously by locals.
Try to remember this is a conservative, communist country where the excesses of western culture are not tolerated.
Mind your p's and q's and you'll have a trouble-free enjoyable visit.
Penalties for drug offences are severe. Under the Vietnamese penal code, a person caught in possession of even a small amount of heroin can be sentenced to death.
There are over two dozen foreigners currently serving life sentences or facing the death penalty for drug trafficking offences. Vietnamese authorities have announced increased security and investigative measures to combat drug trafficking.
When good advice is ignored, travellers should be aware that recreational drugs available in Vietnam can be extremely potent. Party with caution, and always make sure someone knows where you are and what you have taken.
Photography of border crossings and military installations is prohibited and may result in arrest. You should also avoid taking photographs during demonstrations. Leave the military shots to the journo‘s, as the glare of a Vietnamese soldier is incredibly intimidating.
You could be detained if you venture too close to the border with China, Cambodia or Laos without prior written permission from the local authorities.
It is against the law to export antiques from Vietnam without a permit. The Ministry of Culture can provide further advice and any necessary permit.
Gambling, except in government licensed casinos, is illegal in Vietnam. Anyone found to be in violation of this law is subject to steep fines and/or a severe prison sentence. Access to licensed casinos is restricted to holders of foreign passports.
Anyone, Vietnamese or visiting foreigners, engaging in public actions that the Government determines to be political in nature could be arrested and detained. Even your private conversations can lead to legal actions.
U.S. citizens who said they've come to be tourists, but then engage in religious proselytizing have had religious materials confiscated and have been expelled from Vietnam. Sponsors of small, informal religious gatherings, such as Bible-study groups in hotel rooms, have been detained, fined, and expelled, although these outcomes have become less common because of improvements to religious freedom.
Blogging about the Vietnamese government and discussions in on-line chat rooms have also incurred scrutiny from authorities. The distribution of anti-Vietnamese propaganda is considered to be a terrorist offense by Vietnamese authorities. In most cases individuals are detained, questioned, and then released. In the past year, at least ten U.S. citizens were arrested, prevented from leaving Vietnam, and/or deported.