Android 17 got out by opening the gap between Hell and earth. But instead of doing the same, Goku could have used Instant Transmission to get out. Why didn't he do so? Is it because of the fact that he was turned into a child and he could use Instant Transmission only as a Super Saiyan 4 (taking into consideration that Goku could only be a Super Saiyan 4 for a certain amount of time)?
From the Instant Transmission article on Dragon Ball Wiki:
When Goku became a child in Dragon Ball GT, the ability to use this technique was greatly hindered to the point where he just randomly travels to places a short distance away; however, as a Super Saiyan 4, he is able to use the ability to its full potential. When he is given energy by Goten, Trunks, and Gohan during the battle against Syn Shenron, kid Goku is able to properly use Instant Transmission.