I've been rewatching TAS and it's interesting the number of concepts that we now take for granted in Star Trek that seem to have their origin or initial debut in TAS. The things I've noticed so far:
In Beyond the Farthest Star
the hatch to the warp core collapses on Scotty. It seems that the warp core is a common feature on starships from TMP onward, but not TOS.
BONE KNITTING LASER:
No doubt this concept was already being considered in reality. It's specifically mentioned in The Terratin Incident
when Sulu breaks his leg. Bone knitting lasers are regularly featured from TNG onward.
KLINGON CLOAKING DEVICE:
In The Time Trap
, Spock mentions the Klingons having a cloaking device on their D-7 class ships. We first see the Klingon cloaking device in the live-action realm in Star Trek III
. Klingons and cloaking technology go hand in hand from TNG onward.