Summary
- The Guardians of the Galaxy Holiday Special showed Nebula giving Bucky's arm to Rocket as a Christmas gift, but it was never explained what Rocket did with it.
- One theory posited that Nebula's new arm in Guardians of the Galaxy Vol. 3 was made by Rocket using Bucky's stolen prosthetic.
- Another theory stems from Rocket's emotional arc in the MCU, showing how he's changed since Guardians of the Galaxy Vol. 1.
After Guardians of the Galaxy Vol. 3, there's still one mystery surrounding Rocket Raccoon, and it deals with a long-running joke from Guardians of the Galaxy Vol. 1 - what did Rocket do with Bucky's arm? Back in the first Guardians movie, Rocket told Star-Lord to steal a man's prosthetic leg for him during their prison breakout, only for the raccoon to reveal it wasn't actually necessary to the plan. This joke was referenced in Avengers: Infinity War when Rocket offered to buy Bucky Barnes' prosthetic arm, saying, "I'll get that arm," after the Winter Soldier refused.
In the Guardians of the Galaxy Holiday Special, which released before Guardians of the Galaxy 3, Nebula gives Bucky's arm to Rocket as a Christmas gift. Although it's meant as a callback to the Infinity War and GOTG 1 jokes, it created some confusion about how exactly Nebula got the arm. James Gunn explained on social media that Nebula got Bucky's arm by going to Earth and stealing it from him. However, it was never explained - on film or on social media - what Rocket did with Bucky's arm after he finally got it.
Rocket Didn't Use Bucky's Arm To Give Nebula A New Arm
When Guardians of the Galaxy Vol. 3 footage revealed Nebula would have a new arm in the movie, with tech that gives her even more weapons, some theorized Rocket had developed Nebula's new arm from Bucky's prosthetic. However, James Gunn debunked the theory about Nebula's arm being Bucky's stolen limb, saying hers was "way better." This makes sense since Nebula's arm uses some kind of nanotechnology, or an equivalent, to shapeshift into different blasters and other weapons. Bucky's Vibranium arm, though being very strong and indestructible, doesn't have that kind of tech.
Rocket May Have Kept Bucky's Arm Or Given It Back
That still leaves the mystery of what Rocket actually did do with Bucky's arm unsolved. The arm isn't included or referenced at all in Guardians of the Galaxy Vol. 3, not even as an Easter egg in the background of one of the scenes on Nowhere, where the team's new base is located. Since it isn't referenced, the only thing that can be assumed is Rocket still has it somewhere and may use it at a later point.
It's unclear why Rocket wanted Bucky's arm in the first place. When Rocket first told Star-Lord to steal a man's prosthetic leg, he later explained his reasoning was he "thought it would be funny." Given Rocket Raccoon's MCU story arc has him in a much different place emotionally by the time of the Holiday Special and Vol. 3, it's unlikely he'd have the same reasoning, especially given his own history of being tortured and experimented on. In fact, it might make the most sense for Rocket to return Bucky's arm to him at some point after the Guardians of the Galaxy 3 ending, showing how much he's grown since Vol. 1.
That explanation, that Rocket gave Bucky's arm back, would also solve any potential issues with continuity if the Winter Soldier shows up in the Thunderbolts movie with his arm intact. However, until James Gunn or Marvel reveal what Rocket actually did with Bucky's arm, this remains speculation. Now that the MCU is moving forward after Guardians of the Galaxy Vol. 3, hopefully an movie or show will explain this one unsolved mystery.