Eight surprising things that can get you detained at the airport

Arnold Schwarzenegger was held up at Munich airport for nearly three hours after allegedly failing to declare an Audemars Piguet watch valued over €10,000 (£8,580).

The actor and former politician seemed to take the delay in stride, even posing for a photo in the tax bureau office. Turns out, he was planning to auction it to benefit a climate charity.

Under the right circumstances, any of us could be in Arnold's shoes. When packing for an important trip, it is easy to miss travel regulations in the prep. After all, the airport feels like a way station in the much longer journey to get where we're going and back. But it is important to remember that airport staff enforce multiple layers of local and international regulations regarding security, customs, agriculture, health, and more. Certain missteps could have you detained, delayed or worse. If you want your airport transit to be as quick and painless as possible, here are eight things to avoid.

The regulations around travel documents vary by airline and country. To board a plane without hassle, your travel documents can't be expired, and in many cases need to be valid for a certain period before expiration. The logic behind these regulations is that, should your return flight be delayed, you could still board a return later on. It's best to triple check passport and visa validity guidelines before going to the airport. For example, countries such as Thailand, Nepal and Turkey require six months' passport validity from entry, while most of the European Union requires three months, and New Zealand requires one month after your intended departure date.

Also, make sure your photo and bio data are visible and clear. Any rips, tears or water damage could have you grounded until you can get replacement documents. Remember: Travel documents could mean more than just a passport. Some countries require additional documents about prior travel, parental consent (when travelling with a minor), vaccination records or proof of lodging during the stay.

American passport holders can check the latest by destination.

Many travellers may assume that as long as they're not travelling with illegal substances, their luggage will be allowed. Not so. Prohibited items can range from pornography (many countries in Asia and the Middle East restrict it) to firearms. Each country has a designated list of prohibited and restricted items, and some might surprise you.

India prohibits "maps and literature where India's external boundaries are shown incorrectly". Japan prohibits "books, drawings, carvings and any other article which may harm public safety or morals". Dubai bans cooked and homemade foods, as well as three layer fishing nets, crude ivory and rhino horns. US travellers can visit the Transportation Security Administration (TSA) website to check whether an item you want to pack is forbidden. The Federal Aviation Administration (FAA) also offers PackSafe guidance to avoid transporting dangerous goods, including hazardous materials in cargo.

Although many airlines will list restricted items on their website, it's best to check each country's customs websites for the latest. Remember: Some items may be legal in your country of origin and illegal in your country of destination. Airport personnel may have the right to confiscate the item, detain you and deny you entry into the country.

We know "The Terminator" star is tough but Schwarzenegger learned the EU cash controls the hard way. In most countries, including the US, you must declare or notify government officials when entering or leaving the country with large amounts of money, mostly over $10,000, or valuables that cost more than that amount. Jewellery, luxury clothing and even electronics could fit this bill too.

In places such as South Africa and Canada you can complete the declaration forms before travelling and spare yourself fines and delays in the airport.

In 2022, the International Narcotics Control Board published a list of travel regulations around medicines that contain controlled substances, but it is by no means complete. If you're planning to travel with any medications, you'll need to confirm that the ingredients are permitted in the country you're travelling to. Some are allowed with a doctor's note, but others are completely banned. For example, pseudoephedrine, the active ingredient in over-the-counter Sudafed, is considered a controlled substance in Mexico.

Violating the laws of your destination can have serious consequences. The CDC recommends checking with the embassies of every country along your travel route – including transit countries – to make sure all your medicines are permitted. If you're on meds that are restricted in your destination, especilly life-sustaining, psychiatric and/or psychotropic medication, talk with your doctor about adequate alternatives or equivalent substitutions that you may be able to purchase locally after you arrive.

Simply put, there are restrictions on bringing any living creature into another country. Plants, pets and other animals fit that bill. US Customs and Border Protection (CBP) recommends visitors check the Don't Pack a Pest website to learn more about declaring plants, seeds and flowers in the US.

The US Fish and Wildlife Service has a "A Guide for Tourists" that helps travellers avoid bringing in restricted live animals or animal products. The list of generally prohibited items is pretty wild. It includes live birds, medicine from Asiatic black bears, rhinos and tigers, all sea turtle products and fur from sea otters, polar bears and tigers.

For domesticated animals, the rules and regulations vary by airline, country and even time of year. In the US, "not all animals qualify as pets," according to CBP. And even pets may have restricted breeds in certain countries. Jamaica, for example, doesn't allow the import of pit bull terriers.

If your dog can get you detained, then imagine the extra precautions needed when boarding with a snake or other caged animal. Most need to be sent with pet transporters, who can ensure that your animal meets all the vaccination, quarantine and import/export restrictions along your route. Check with your airline and embassy to confirm the latest.

Things that burn – cigarettes, lighters and vape pens – are generally restricted on most airline carriers, which provide instructions on how to transport these safely, if at all.

Travelling with things that burn and explode can get your flight cancelled. Fireworks, even the smallest sparklers, are not permitted aboard aeroplanes. Friction can cause the fireworks to ignite during the flight, posing a safety risk to passengers and crew. In the US, passengers who violate these regulations can face civil penalties of up to $75,000 per violation. Additionally, anyone importing them for sale may face criminal charges.

Whether you're travelling for a birthday, New Year's or wedding celebration, don't travel with anything that you're meant to light on fire.

Are you thinking of having one or two for the road? Think twice. If the ground or cabin crew thinks you've had too much and are a danger to yourself and others, that could be cause for delay. According to the FAA, "The boarding of a passenger who appears to be intoxicated is a violation of Section 121.575 of the Federal Aviation Regulations (FAR)." This makes ground crew responsible for stopping anyone who may have had too many before takeoff.

On board, US federal law prohibits passengers from drinking alcoholic beverages that were not served by a flight attendant. Further, the FAA has a zero-tolerance policy on unruly behaviour from flight passengers. Running afoul of this policy for any reason could result in being fined, placed on an airline's internal no-fly list, or referred to the FBI for felony charges.

Remember, alcohol use is strictly prohibited in some countries, where you can be detained or jailed for being under the influence or carrying it in your luggage.

While every case is different, unsettled legal matters could derail your travel plans. In many countries, airport security and immigration officials can access various databases that identify individuals with a criminal record and outstanding warrants.

"If you have unpaid fines and try to leave or come into New Zealand, the police can stop you at the airport," reads the Ministry of Justice website for New Zealand. In the US, anyone with over $2,500 in unpaid child support is restricted from even getting a US passport.

Make sure you're on the right side of the law before trying to board a plane. If you have a pending civil judgment or criminal record, check with your legal counsel to verify that you are allowed to travel to your destination without any restrictions. Resolve warrants and fines before flying. Carry proof of the resolution to avoid potential embarrassment and detention at the airport.

---

Join more than three million BBC Travel fans by liking us on Facebook, or follow us on Twitter and Instagram.

If you liked this story, sign up for the weekly bbc.com features newsletter called ”The Essential List”. A handpicked selection of stories from BBC Future, Culture, Worklife and Travel, delivered to your inbox every Friday.