Goku Being An Alien Is Foreshadowed
As a Dragon Ball fan, you will invariably come across another fan theorizing that Akira Toriyama had actually conceived of Goku being an alien far earlier than as we see it play out during the Saiyan arc, courtesy of the following image:
The scene in question comes from episode 36 of the original Dragon Ball television series, adapting Goku’s assault on Muscle Tower during the Red Ribbon story arc. In this episode, Goku encounters Sergeant Metallic. When the evil army’s robot “scans” Goku, the above first-person readout is shown to the viewer.
It pretty concretely says “alien” (or, well, “LOOK ALIENS”) there… but what does it mean, and in particular, is it a foreshadowing reference to Goku being an alien?
The Text Source
This particular text is all lifted wholesale from the 1979 film Alien (directed by Ridley Scott and starring Sigourney Weaver as Ellen Ripley).
When Ripley accesses the main computer system (“Mother”) toward the end of the film, this text is displayed on screen:
The usage of this text in Dragon Ball is commonly referred to as just “filler text”: text displayed, generally in a language other than the language the production is originally being scripted in, that literally fills up space in a cool yet non-distracting way.
In this case, Metallic’s “scan” of Goku exists solely in the television series, and was not present in the original manga by Akira Toriyama.
… but that said, were there any hints of Goku being an alien earlier than the actual Saiyan arc?
The Manga Lines
Fans often point to a line from Oolong way back at the beginning of the series: in chapter 22, after the battle with Pilaf and Goku’s return to normal from his Great Ape transformation, Oolong wonders if Goku might actually be an alien.
It’s a bit of a rhetorical question, and the group immediately moves on, thankful that they are all safe.
The next line happens much later in chapter 159 during Goku’s battle with Demon King Piccolo, where the villain is astonished that a mere human can contend with him; in response, Goku wonders — with regard to his tail — if he is even human at all:
This exact same exchange is kept effectively verbatim in episode 122 of the Dragon Ball television series.
Was this Toriyama foreshadowing Goku being an alien far earlier than anyone expected…?
The English Localization Obfuscations
Unfortunately, both Viz’s English translation of the manga and (perhaps in a more expected manner) FUNimation’s English dub of the television series write around or otherwise confuse the direct meaning of Goku’s line back to Piccolo.
Viz condenses the dialogue perhaps for clarity and space, but in the process inadvertently removes the important “human” aspect of Goku’s line, despite being addressed by Piccolo just one panel earlier. You can legitimately argue that the meaning of Goku’s statement is still implied here in the Viz translation, but the direct nature is lost:
Piccolo: This… shouldn’t be happening… That a mere human can stand up to the Great Demon King Piccolo…
Goku: Heh heh heh… You didn’t see my tail, didja?
FUNimation’s English dub is victim to its usual rewriting, though it somehow manages to keep the “tail” part:
Piccolo: I’ve fought all over the universe and I’ve never met anyone with the strength to face me in hand to hand combat!
Goku: Well I guess I’m not like other people because I’ve got a tail…
Thankfully, the subtitle translation for the television series’ original Japanese version produced by FUNimation (as opposed to their English dub noted above) is adapted faithfully (and in this case, somewhat critically more literally).
When Did Toriyama Decide…?
Toriyama details his “deciding on aliens” timeframe during the fourth Daizenshuu‘s “Super Interview” (the Daizenshuu were a series of guide books released in the mid-1990s concurrent with the end of the original serialization, and the original seven each had an exclusive interview with Toriyama):
Speaking of Piccolo, did you think from the beginning of his background as a Namekian alien?
Of course, I didn’t think that at all. (laughs) The Saiyans were like that as well. When I thought up Goku’s tail and the Ōzaru (“Great Ape”), I didn’t think Goku was an alien or anything. Piccolo either. Because I thought that up when God came out.
In this single response, Toriyama concretely explains away Oolong’s mention, and places his decision point at a somewhat-nebulous time later in the series.
The question is here is: when he says “when God came out,” does he literally mean he did not decide upon things until around that actually happens in chapter 164? Or, does he mean around the time that God starts getting mentioned in earnest, which is two chapters earlier in 162? Goku’s line in chapter 159 is mere weeks before these events, so perhaps Toriyama’s “when God came out” refers to this rough timeframe as a whole…
… in which case, we have to wonder if Goku’s line went on to inform or guide Toriyama’s vision, or rather if it had already been decided upon at that moment…!
…… or is Toriyama only referring to the fact that he decided on Piccolo being an alien at this point, and the idea for Goku as an alien came even later…?!
Based on the structure of Toriyama’s answer, it’s most likely that when he says “because that I thought that up” he’s referring just to Piccolo, rather than Piccolo + Goku; there is a change in subjects at that point in his answer (from the Saiyans/Goku to Piccolo, the original point of the question posed to him).
That said, in terms of raw manga chapters and the production schedule, the Saiyan arc is less than a year off from the climax with Demon King Piccolo — though Toriyama admittedly writes by the seat of his pants, there are clearly some ideas percolating here, and they’re happening in a relatively short timeframe considering the overall length of the franchise’s run.