First of all: It turned out to be true once again.
It is always better to be a female furry nanomachine robot super powered child.
Off the top of my head, ignoring some stuff like the Dragon Ball Radar detection technology, the biggest deal should be
capsules. If it is not man made pocket dimensions using only science, then it is straight up magic needing only technology! In cannon, in story, they mention that a capsule containing a massive water tank, one that can contain tons of water, would still be transportable by a martial artist after being filled up and shrunken back down to pocket sized.
Not just hard structures like vaults and barrels and tanks and stuff, complicated shit like space ships, houses with their own internal electronics and loose goods, tools, cars and vans, tractors, etc. etc. etc.
Did I mention those space ships can transverse the stars without Warp, teleportation, etc... While including artificial gravity for training purposes far greater than any planet? Without running out of power, or indeed ever needing to be refueled? Space ships in DBZ are nuts.
Oh, there is other crazy shit too. Time machines, perfect cloning, the ability to make a cyborg that turns any random person into a monster able to fight gods while being attractive, young, immortal, and still able to breed with humans... And other stuff that is just plain impossible like
Senzu beans, magic clouds vehicles, extendable poles with infinite mass but very little weight, fans that can blow down a forest fire, etc. etc. etc.