Executive Meddling: The entire Android and Cell arc is the result of Toriyama's former editor, Torishima, not liking the character designs of the villains.
Missing Episode: Material was cut in the original version of Z's Ocean dub of seasons 1 and 2, mostly for violence, but sometimes smaller arcs were too.
In Hungary, where Moral Guardians have forced the series off the air in 1999, episodes 137+ were first released officially only in late 2013, although they've been available on video hosting sites since 2009. Episodes 227-231 were still missing until finally being shown in January 2014.
In the Latin-American Spanish dub, Laura Torres plays both child!Goku, child!Gohan and child!Goten. Mario Castañeda, who voices teenaged and adult!Goku, voices Bardock and Tullece/Turles.
In the FUNimation dub, Chris Sabat plays Vegeta, Piccolo, and Yamcha. While the latter doesn't have too much screen time, it doesn't change the fact that Sabat is talking to himself a majority of the time, especially through most of the Saiyan arrival scenes.
Notable that Sabat once said that he wanted to get Scott McNeil to be Piccolo in the dub of Kai, which would've largely averted this trope the second time around. Flying someone all the way over from Canada to Texas for a voice acting job is unfortunately not always feasible...
Goten and Videl in the English dub, are both are voiced by Kara Edwards.
In the Japanese version, both Pan and Videl are played by Yuko Minaguchi
The English Dub originally started out using actors from the Canada-based Ocean Group, and they've continued their own dub of the series outside of the U.S.. Out of all the V As, Raditz's original English actor is probably best known as Randy Disher on Monk.
Speaking of Ocean Group, if their Videl ever said "Sit Boy!", would there be an audible thud somewhere?
The Other Darrin: As explained, doing all those fight scenes really strains the throat. Goku's Super Saiyan 3 transformation had non-stop screaming for the better part of an episode. And a few seiyuu did die by the time Kai aired.
In the Latin American dub, nearly every voice actor was replaced in Kai, but the original VA's were brought back for Dragon Ball Z: Battle of Gods
The German dub replaced Santiago Ziesmer with Oliver Siebeck as Vegeta. The fans preferred Siebeck.
Truth in Television: At the beginning of the series, a plot point of the fight against Raditz is that when Goku and Piccolo's energy techniques raise their maximum power by concentrating that power into a single point. In real life, techniques in martial arts really do work this way, having the concentration of an attack aimed at a very small area to maximize the attack power of the striking area; with follow-through and the striking motion being concentrated in order to create no wasted motion. This concentration of energy and power onto a single point is how martial artists are able to strike through concrete and wood.
According to a one-off line in the FUNimation dub, Vegeta wears a size 9 boot.
Along with Fairy Tail, Toriko, and Attack on Titan, Dragon Ball Z is currently one of the most requested shows for Toonami on [adult swim], mostly due to it being one of the block's more famous shows when it was still on Cartoon Network. Unfortunately, the chances of it airing are slim to none due to Nicktoons holding the cable broadcast rights to the show note it aired during the April Fools Day 2012 Toonami broadcast, but that was because the production crew simply asked Funimation if they could borrow an episode for a one-night event, promoting the DVD releases in return.
Ironically enough, Dragon Ball Z (as well as Dragon Ball Z Kai) technically did make it on the new Toonami… over in Asia.
Cooler's Revenge is set to air on May 24th, in celebration of the 2nd anniversary of Toonami's revival on [adult swim]. Still no word on the show itself, however.