In the Pampas of Argentina, Mickey rides along on a rhea. He soon encounters "Cantina Argentina," apparently serving as the local bar and restaurant, as well as his destination. Mickey proceeds to enter the establishment and takes a seat at a window. He apparently just wants to relax with some beer drinking and tobacco smoking. Also present at the establishment are Black Pete (later renamed Peg Leg Pete, or just Pete), a wanted outlaw and fellow customer for the time being, and Minnie Mouse, the barmaid and dancer of the establishment, at the time performing a tango. Both customers soon begin to flirt with Minnie and to rival one another. At some point, Pete proceeds in kidnapping Minnie (and causing her to lose her shoes) and Mickey realized this and tried to fight Pete but he spits at him. He then attempts to escape on his horse, in which it didn’t go well as he accidentally landed on his horse when it jumped over a rock. Mickey gives chase on his weak rhea, in which he quits riding it after thinking put starch on a rhea is a bad idea. He soon catches up to his rival at his house and they proceed to fight with swords. Mickey emerges the victor of this joust after hitting Pete in the head with a white caldron that he found under a bed. The finale of the short has Mickey releasing Minnie from the chains and he and his new lover riding the rhea as well as kissing for the very first time into the distance.
In later interviews, Iwerks would comment that Mickey as featured in The Gallopin' Gaucho was intended to be a swashbuckler, an adventurer modeled after Douglas Fairbanks, whose film The Gaucho served as the primary inspiration of the short. This short marks the first encounter between Mickey and Black Pete, a character already established as an antagonist in both the Alice Comedies and the Oswald series. Based on Mickey and Minnie acting as strangers to each other before the finale, it was presumably intended to feature their original acquaintance to each other as well. Modern audiences have commented that all three characters seem to be coming out of rough, lower-class backgrounds that little resemble their later versions. Consequently the short is arguably of some historical significance.
However the feature characters of the short were obscure at best. Mickey was at first thought to be much too similar to Oswald, resulting in the apparent lack of interest in him. Disney would soon start to contemplate ways to distinguish the Mickey Mouse series from his previous work and that of his rivals. Minnie's role as performer and damsel in distress is solidified in this. It is also the first time she wears her distinctive oversized high heeled pumps, although they fall off almost offscreen when she is kidnapped and she spends the rest of the cartoon shoeless. Mickey is also seen wearing shoes for the first time, adding more anthropomorphic traits to the characters which would progressively become more apparent as the years went on.
At the time of its original production though, Walt again failed to find a distributor. It would be first released on December 30, 1928, following the release of another Mickey short. Reportedly Mickey was at first thought to be much too similar to Oswald and this resulted in the apparent lack of interest in him. Walt would soon start to contemplate ways to distinguish the Mickey Mouse series from his previous work and that of his rivals. The result of his contemplations would be the second Mickey short to be produced, the first to be released and the first to really draw the attention of the audiences: Steamboat Willie.
Most of the gags in this cartoon were reused from "Harem Scarem" an Oswald the Lucky Rabbit short that is still lost to this day.
Minnie transitions from foil and free-spirited to damsel in distress.
This marked the debut of Pete in a Mickey short.
However, he is considered to be "Black Pete" in this short.
Pete also transitioned from a bear to a cat, as classified with a more cat-like face and whiskers.
This is the third Mickey short to be released
However, this is actually the second produced short, as Walt Disney failed to find a distributor, just like in Plane Crazy, the first produced but fourth released short.
This strangely marked the first and only time Mickey and Minnie evolved halfway through the short, as their eyes changed from big eyeballs with black pupils to smaller black ovals which would later be used in Steamboat Willie that same year.
Minnie's shoes are considered to be a lot bigger as before becoming shoeless, her heels slipped out of her shoes in a total of 100+ times with most of the gag not being noticed at first glance.