Believe it or not, there are millions of coins in circulation right now that are worth far more than their face value. We've rounded-up some of the most valuable US, UK and European examples to give you an idea about what to look for when you're home and away. Study them well and make sure you double- and triple-check your change in future.

Decorated with the iconic WWF panda and 50 other animals, this rare 50p was released as a special collectors edition in 2011. Special versions of the coin are up for grabs for around $1,300 (£1,000) on eBay, but even just any old version is worth a lot, with some coins selling for more than $13 (£10).

This 1913 nickel was first pressed without any approval from the U.S Mint, after it had switched the design from lady Liberty to the profile of a Native American. Most coins got caught out, but five of the sneaky five-cent pieces managed to make their way into the hands of the public. The most expensive was bought for a staggering $3.7 million (£2.9m) and if one is found in mint condition, it could be worth as much as $20 million (£16m).

Plenty of these US error pennies are floating around in circulation, so there's a good chance you might come across one. The 'In Liberty' and 'In God We Trust' inscriptions were double engraved by accident, creating a blurred effect. The coins have a value of $50 (£39) a piece.

Only 485,500 of these special edition Commonwealth Games Northern Ireland £2 coins were minted – a relatively tiny run in coinage terms – and as a result, each one can fetch £25 ($31) or more these days.

A number of pennies were minted in 1997 showing Abraham Lincoln with an extra earlobe. The machine double minted that part of the design in error. These coins are now worth up to $250 (£194) a piece.

The rarest sterling coin in circulation, the 2008 Kew Gardens 50p piece had a limited run of just 210,000. The shiniest, most pristine examples can command prices up to £120 ($155), so keep a keen eye out for these coins.

This amusing error featured on thousands of 2005 Kansas state quarters – according to the state Mint, the 'T' stamp was over-lubricated and failed to make a strong impression on the coins. Collectors pay up to $100 (£78) for these error coins.

Thousands of undated 20 pence pieces fell through the net in 2008 following a mistake in the minting process. Be sure to check your change because these dateless coins go for up to £200 ($258) each on eBay.

Since 1980, all US dollar coins apart from cents have featured a mint mark above the date, with the exception of a few accidental batches. Thousands of dimes minus the mint mark were released by the Philadelphia Mint in 1982, and these coins are now worth up to $300 (£233) a pop.

All twopences featured the words 'New Pence' up to 1981 and 'Two Pence' thereafter. However, a batch in 1983 was accidentally minted with the 'New Pence' lettering. These coins are worth up to £700 ($902) each.

The 2004 Wisconsin state quarter features a corn husk with four leaves. An extra leaf was added by mistake to a small selection of coins – these five-leaf coins sell for up to $300 (£234) each.

An unspecified number – thought to be in the thousands – of presidential dollar coins missing the 'In God We Trust' inscription around the edge were released by the Philadelphia Mint in 2007. These 'godless' coins have a value of up to $300 (£233) a piece.

Several 1971 'silver' 2 pence pieces have been discovered lurking in small change and have fetched up to £1,350 ($1,740) at auction. A cupronickel rather than copper blank was left inside the minting machine in error, creating a small number of freak coins that quality control overlooked.

This coin is an extreme example of a doubled die error. The lettering in particular appears twice and is overlapping. If you come across one, you're in luck – a 1972 double die Lincoln penny can sell for up to $500 (£388).

A minting machine calibration error resulted in a wider space between the 'A' and 'M' on hundreds of 1 cent coins back in 1999. If you spot one in your change, it could be worth up to $500 (£388), so keep your eyes peeled.

In 2012, the Royal Mint released a 50 pence piece to commemorate aquatic sports at the London Olympics. The original design (pictured on the left) showed the swimmer with water obscuring the face. This was tweaked to make the face more visible (pictured on the right) but not before 600 coins with the original design were released. These coins are now worth up to £3,000 ($4k) each.

In 2005, 900 Jefferson nickels were engraved with what looks like a spear piercing the bison's belly, following a die gouge error. These rare coins – which shouldn't be too tricky to spot – go for up to $1,250 (£970) at auction.

Commemorative €2 coins tend to be worth more than their face value, especially the rarer examples from smaller countries such as Luxembourg, Monaco and Vatican City. Collectors will pay around $150 (£116) for this 2006 €2 from Luxembourg for instance.

This bizarre-looking 2001 quarter was struck twice in error, creating a strange double image. Most were intercepted, but a few ended up in circulation and could be worth up to $3,000 (£2.4k).

In 1970, the Philadelphia Mint issued a batch of pennies with a doubled die on the head site, defining the engraving. These pennies fetch up to $3,000 (£2.4k) at auction.

The lettering on hundreds of 1955 cents was doubled in error, creating a fuzzy effect. These pennies, which are still found in circulation, have garnered prices of up to $5,000 (£3.9k).

The €2 coins that were minted by the Vatican City to mark the Catholic Church's 20th International Youth Day in 2005 are now worth $130 (£100) each. Only 100,000 of the coins were ever released.

Silver dimes were phased out in 1964, but several were minted in early 1965 and these shiny coins, which still crop up now and again, attract prices at of $9,000 (£7k) or more at auction.

In 2002, Zecca di Stato, the company that mints euro currency in Italy, released thousands of 1 cent coins mistakenly depicting Turin's Mole Antonelliana instead of the correct Castel del Monte in Apulia. These error coins fetch up to a staggering $7,300 (£5.6k) each.

These pennies were thought be forgeries until the Philadelphia Mint realized its mistake. Abraham Lincoln's head is more prominently outlined on these coins. Extremely rare but still in circulation, they are worth up to $35,000 (£27k).

All 1943 US pennies were minted in steel as copper was required for the war effort – apart from a selection of 40. Very occasionally, these 1943 copper cents turn up in people's change and can be worth a staggering $1 million (£754k) in mint condition, nearer $10,000 (£7.5k) to $100,000 (£776k) if damaged.

This commemorative €2 coin depicting Princess Grace of Monaco enjoyed a relatively small mint run – only 20,001 were produced – hence the inflated value. Each coin sells for around $330 (£256).