Hello. Though I'm new on this site and I'm only 17, I have been thoroughly interested in classical history for most of my life. I happened to find this site by accident in my own quest for Rtw realism. Coincidentally, I had just been making an interesting list of things, units, used in history that are not prevelant in the game and should be. I humbly present my list of historically accurate units to which I can add inumerable details should they be requested.

Ships:
Pentekonter
Hepteres (Spetireme)
Liburnian

Siege Engines:
Sambuca
The Fire Raiser
Helepolis

Race Specific:

Greek:
Sacred Band
Elephants
War elephants

Macedon:
hypaspists
gastraphetes
ballistas

Ptolmeic Empire:
elephants

Seleucid Empire:
hypaspists

Carthage:
chariots (including four horse ones)
Temple of Moloch

Gaul:
chariots
Nobles (phalanx/spearmen)

Germany:
javelin armed light cavalry

Romans:
auxilia cavalry archers
roman cataphracts
(these two may be a little out of time frame)

Mercenaries:
Thracian peltasts, slingers and javelinmen
Libyan chariots
Etruscans
Mamertines
Scythian foot archers