Blooper

During the bar scene in Greenland, the level of Walter's beer goes up after he is served.

When Walter walks with Cheryl to see the final cover of Life magazine, Walter's shoes are black. In the next shot they are brown, and then black again.

When Walter shows Cheryl's son skateboard tricks in the park, Walter's briefcase moves from the right side of the park bench, where he puts it down initially, to the left side when he and Rich are in the background and Cheryl is on the phone.

When Walter and Cheryl walk on the sidewalk toward the camera, all of the background extras change position when a car passes. A red-haired woman on the left moves several feet backward, and an Asian woman on the right disappears.

When Walter longboards down the mountain in Iceland, he wears Nike running shoes in the close-ups, and Nike SB (skateboard) shoes in long shots.

After jumping into the ocean off the coast of Greenland, Walter is attacked by what appears to be a Great White shark. The northern limit of the Great White's natural range is far south of Greenland and Iceland. The Greenland shark, which lives in sub-Arctic waters, is a very different animal, approximately the same size but blue/green in colour and with a tiny dorsal fin.

When Walter Mitty visits Sean O'Connell in the Himalayas, O'Connell uses an old Nikon F3/T camera with what appears to be a Nikon 400/2.8G lens attached. While it's technically possible to use that combination, the lens has no aperture ring and no way to set the aperture on that body. A professional photographer would not use this combination, especially if they preferred vintage equipment.

Walter's resume mentions helicopter free diving in the North Sea. Walter's helicopter ride between Greenland and Iceland wouldn't have taken him over the North Sea.

Arabic is an official language in 26 countries, not 40. "Ragul Kawy" means strong man, not strong little man.

Before Sean lets Walter take a peek through his camera's viewfinder, he accidentally touches the lens and brings it out of position. Walter wouldn't have seen much without readjusting the lens.

The dogs shown outside in Greenland are not authentic Greenlandic sled dogs, the only dogs allowed in Greenland. This is only true north of latitude 66, and Nuuk is well south of this. In fact, Greenland Dogs are likewise not allowed south of the 66th, specifically to avoid interbreeding.

Walter jumps from a helicopter into the ocean. A person can remain conscious for nearly 15 minutes in water at 2 degrees Celsius, and survive for nearly 45 minutes, if they don't suffer cardiac arrest on immersion.

In a country where two-thirds of Americans do not hold a passport, a man whose core identity involves never having gone anywhere would not be able to produce a passport so readily.

But this is not a character goof at all. Walter Mitty's core identity is not about "never having gone anywhere", but rather about "always dreaming of going somewhere someday". Furthermore, he is a meticulous, diligent man with a well-paying job and without habits of spending money on frivolous things (such as trendy new clothes every year); so it would make sense that he can and would maintain a valid passport, just like how he would for example also always pay his insurance bills.

In the beginning of the movie, Walter and Cheryl reveal that Sean is an old school person and doesn't have a phone. But when Walter meets the fisherman, one of them tells him that Sean taught him and gave him tips for his Instagram. It's possible that he was just giving him photography tips, as opposed to specific Instagram tips.

Walter, who had never been to anyplace but Phoenix, would likely not have had a passport, and could not have gotten one quickly enough to leave for Greenland immediately, it's entirely possible that he had previously gotten one with the dream of traveling, but never found the courage to do any.

When Walter first calls Todd about his Eharmony profile, Todd says he is "looking at his page now," despite never asking Walter for his name.

While it is highly unlikely that a man who never travels has an active passport, we later see from his checkbook entries that Walter paid to have a passport expedited for $400. While the fees may be accurate, it can still take up to two weeks for an expedited passport to arrive.

When Walter jumps into the helicopter, we can see Cheryl on the ground still "playing" the guitar, as Space Oddity is heard on the soundtrack. Cheryl is clearly not playing the guitar, her fingers is not even touching the strings.

When the volcano eruption alarm goes off in Iceland, the film shows 3 klaxon-style horns, not the sirens heard on the soundtrack.

When the helicopter pilot gets ready to take off, the Bell 47J Ranger has a Lycoming piston engine, but makes the high-pitched whistle of a gas turbine revving up.

The fishing vessel crewmen show Walter a wildly inaccurate map. It shows the Eyjafjallajökull volcano nestled deep in a fjord in what appears to be the Westfjords region in the northwest corner of the island. Eyjafjallajökull is located on the coastline in the Southern Region.

Immediately after arriving in Afghanistan, Walter walks in front of mountains, then a waterfall. Both shots are from Iceland. The mountain is Hvannadalshnúkur. The waterfall, Skogafoss, is at the foot of Eyjafjallajökull mountain, where Walter had already been.

Walter Mitty flies to Greenland in a jet. He lands in Nuuk in an Airbus 332. Air Greenland, the airline pictured, flies its only jet, an Airbus 332, between Copenhagen, Denmark and Kangerlussuaq, Greenland. The Nuuk runway is too short for an Airbus 332 to land.

In his curriculum vitae, Walter states that he has bathed in the North Sea. Actually, he fell down from the helicopter into the Denmark Strait, which is not part of the North Sea.

Walter flies from New York to Nuuk, Greenland on Air Greenland. Air Greenland is strictly a domestic airline that only operates flights within Greenland. It's single airliner (the Airbus A330-200 shown in the film) only operates transatlantic routes to Copenhagen, Denmark. There are no direct flights to Greenland from the USA or Canada. The only alternative between Greenland and USA/Canada is Air Iceland/Icelandair with a plane change in Iceland.

When Walter jumps from the helicopter to the water he's supposedly have his phone in his pants' pocket. There's no way a flip phone like the one shown several times could be submerged more than one minute and still functional.

"Ragul Kawy" means strong man, without "little."

Several characters, including Walter, call the repeated David Bowie song "Major Tom". It's actually called "Space Oddity". (Major Tom is a fictional astronaut referenced in David Bowie's songs "Space Oddity", "Ashes to Ashes", "Hallo Spaceboy", and "Blackstar".)

"Major Tom" is actually an entirely different song by Peter Schilling released in 1983. It tells the ongoing story of the Major Tom character from the Bowie songs.

When Walter writes his on-line resume, he says he earned his keep as a "boatswain (unpaid deckhand)" on an Icelandic fishing trawler. A boatswain is a senior crew member, not a rookie deckhand. Walter tracked the boat down by flying to Nuuk, its port of registration, so it was a Greenlandic vessel, not Icelandic.

When Walter and Cheryl are in the park talking about where Sean might be, Cheryl says someone sent "1090s" to New Jersey and Greenland. She probably means 1099s, pay records for non-employee contractors.

When Walter performs skateboard tricks in the park, the actor is quite clearly a stunt double.