Any idea how....

[Evil Vegeta]

Bojack knows anything about Goku and his connection to Gohan?

I just always found this part a bit...odd.

 

[Papasmurf]

I guess he was really interested in how North kaio died and found out some nigga named Goku caused his death because his son fucked up

 

[Evil Vegeta]

Word does spread throughout the universe fast.

 

[Jerk Store]

Duh! The Spacey Times..... I have my subscription.

 

[Captain Cadaver]

Maybe he could here what was going on around Kaio's planet when sealed under it and pieced things together. Gohan might have mentioned his father as well, though I don't care enough to rewatch the movie.

 

[Let's Go Fearless!]

Maybe he can read Gohan's mind.

 

[Captain Cadaver]

Namek Arc Goku could just by having trained in 100x Earth's Gravity, so I wouldn't put mind reading as an impossibility for anyone relevant after the Freeza Arc.

 

[Southern Gothic]

Were Bojack's minions trapped in Kaio's planet as well? If not, they could have been keeping track of events on Earth. Goku is off and on famous, so no surprise that they would know a little about him.

 

[Papasmurf]

They were probably all trapped except for the guy with the bushy moustache