During the course of Avatar: The Last Airbender, there are many failed attempts by the heroes to take down the Fire Lord and stop the Fire Nation once and for all, one of those being their best chance at success, The Day of Black Sun.

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Known as the darkest day in Fire Nation history, this eclipse doesn't come around very often, and Team Avatar would have been foolish to squander the opportunity to defeat the Fire Nation while they were effectively powerless. As this is a two-part episode, the longer duration of the story can cause some details to be missed by viewers, or to be obscure enough that they may not even realize they exist in the first place.

10 One Of The Prison Guards Was Voiced By Serena Williams

Avatar has been no stranger to casting famous voices in its series, from JK Simmons as Tenzin to Aubrey Plaza as Eska, but The Day of Black Sun had a surprise guest that many fans may have missed during the prison scenes with Iroh. The female guard, Ming, who Iroh tells to stay home during the eclipse, is played by none other than the former number one tennis player, Serena Williams. She would also come back to the Avatar universe in The Legend of Korra as one of the fire sages during Avatar Wan's backstory.

9 Appa's Armor Was Hinted At Earlier In The Season

As the loyal steed and animal guide for Aang, it makes sense that someone in the show would have made the flying bison something to protect himself during the invasion of the Fire Nation, something that Sokka hinted at during the season 3 episode, The Runaway. As the group is collecting large amounts of money by scamming local scammers in the Fire Nation, Sokka says he would use the funds they have collected so far to make armor for Appa, to which Toph obliges in giving him some of her winnings.

8 One Of The Few Times Appa Hasn't Taken Off To Yip-Yip

Sokka In Avatar The Last Airbender looks determined

Throughout the series, Appa has shown to be far more intelligent than any real-world bison, being able to understand most human speech and body language as if he were human himself. The only exception to this seems to be that he won't take off unless someone says "yip-yip," but even that isn't set in stone.

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During The Day of Black Sun, Part 1: The Invasion, Sokka leads the invasion force in a wedge formation to break through the Fire Nation's defenses, and Appa takes off when he yells "Charge!" rather than his usual command. He has done two other times before, both being during the heartbreaking episode, Appa's Lost Days.

7 "Pants Are An Illusion"

As the invasion force lands on the makeshift docks created by Aang and Toph, the viewers are treated to the return of many characters from past episodes. This includes Hippo and The Boulder from the underground fighting ring, and the swampbenders that the group met during their visit to Foggy Swamp. One of the swampbenders, Huu, says that "Pants are an illusion, and so is death," which is a play on a previous line spoken by him, in which he says that "Time is an illusion, and so is death."

6 The White Jade Tea Is Poisonous

One of Iroh's most recognizable characteristics is his love of tea, something that didn't go unnoticed by Ming during his imprisonment in the Fire Nation. During her rounds to bring Iroh his food, she mentions that she added some white jade tea to his meal, knowing that he likes it. Unfortunately, as shown in the episode The Cave of Two Lovers, the white jade plant is poisonous and often confused with the white dragon bush, a mistake that Iroh himself made with near-fatal consequences. Maybe Ming wasn't as nice as she appeared to be.

5 Peanut Bombs

When Team Avatar first meets the mechanist, he is shown to have invented some fairly strange versions of real-world inventions, including a candle that acts like a clock and his submarines, but his most realistic invention was actually the peanut bombs.

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Processed peanut oil is used to make glycerol and, by extension, nitro-glycerol, a major ingredient in the creation of dynamite. He may be a mad old man, but he was on the right track to creating some devastating firepower for the resistance group.

4 The Lighting Is Brighter During The Eclipse That It Should Be

avatar eclipse

During The Day of Black Sun, Part 2: The Eclipse, the eclipse finally comes into effect and the sun is blocked out by the moon, taking away firebending for a few critical minutes. During this time, the lighting should have been similar to what has been used in past episodes that have taken place during dusk or even night time, but the lighting during the eclipse was much brighter than what has been used during either of those times of the day. It's one of the few oversights that this two-part episode has, with the other concerning the visibility of the eclipse itself.

3 Not Everyone Should Have Been Able To See The Eclipse

Avatar Bumi Eclipse

During the eclipse, an imprisoned King Bumi takes the opportunity to liberate Omashu and singlehandedly release himself, destroying the Fire Nation military outposts and effectively forcing them from his city. The problem is, he shouldn't have been able to see the eclipse at the same time as the invasion force did, as he was far away in the Earth Kingdom at the time of the invasion, and theoretically wouldn't have been able to make his escape at all.

2 Aang's Speed Reduction

As an airbender, Aang is noticeably more nimble than practitioners of other bending types, which is most notable when he uses his airbending to allow himself to run much faster than a normal human should. During the invasion, Team Avatar chase Azula through a tunnel network under the main city, where they suspect that the Fire Lord is hiding to wait out the eclipse. In this chase scene, Azula easily outpaces Aang even without her bending which, while it makes for a more dramatic scene, doesn't follow the show's continuity.

1 The Eclipse Duration Is Accurate

Avatar likes to take some creative liberties when it comes to realism in the series, as any fantasy series would, but some aspects are grounded in realism that goes largely unnoticed by viewers. During The Eclipse, the amount of screen time between the sun being completely covered by the moon and when Ozai bends lightning and Zuko is around 8 minutes, the same amount of time that Hakoda claims the eclipse will last. Not only that, but the average solar eclipse on Earth lasts around 8 minutes, the same amount of time the eclipse lasts during The Day of Black Sun.

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