the dub had a surprise cross-region one late in the story: Scott McNeil as Hohenheim!
Earlier than that, Johnny Yong Bosch, typically a Los Angeles-based actor, makes a surprise cameo as a supporting character for one episode.
The series is purported to be one of, if not the only anime series to be dubbed by actors hailing for all four major dubbing cities: Dallas, Los Angeles, New York, and Vancouver.
It's easier to list Texas-based voice actors who haven't been in Fullmetal Alchemist at some point than those who have.
In the Japanese version, an amazing amount of the cast had been involved in Mobile Suit Gundam SEED, which Fullmetal Alchemist had immediately followed in the popular (at the time) Saturday 6 p.m. timeslot after SEED had finished airing. The tradition would be continued with Mobile Suit Gundam 00 and Fullmetal Alchemist Brotherhood.
In Germany Roy is Johnny Depp (voiced by David Nathan who is the German voice actor for most of Depp's stuff.)
Brotherhood is not the only instance of Gundam and Fullmetal Alchemist sharing several voice actors, the original anime also featured several seiyuu from Gundam SEED. So it's probably a safe bet that if there is a FMA anime, then they will most likely follow after a Gundam series, and have several voice actors in both.
Both the sub and dub of Brotherhood have some of the Darker than Black cast.
Ling Yao is the son of the Shinigami, while Shou Tucker spends his spare time swinging around a deathscythe who happens to be Ed. Along with this, Hawkeye wears an eyepatch and is in love with Tucker. In the meantime, Roy Mustang doubles as an ineffectual magical werewolf and Selim Bradley as a flamboyant blue-haired ninja. Major General Amstrong is a spider, and Winry has a flame-throwing cheese grater for a weapon. Kimblee enjoys listening to music while Scar has gears on his legs for weapons. Guess what? They're still enemies. Meanwhile, Father is also an undead teacher in his spare time, Greed is a transforming legendary sword that's annoying as hell, and Lust is suddenly...flat chested. Mei Chang grows up to be a transforming weapon and Alphonse Elric doesn't knowhow to handlethis.
Don't forget that Death is also Hohenheim as well as Tamaki's dad (Ouran's Chairman).
Hoho and Hohopapa for Hohenheim, Scarbro for Scar's brother, Sexyhobo for Scar (no, really!), Shinri-kun or Truth-kun for the guardian of the Doors of Truth, Greedling or GreedLin for Greed once he takes over Lin/Ling's body (which is used by Ed as a Shout Out to the fanbase at one point), etc.
Also Bob the Blob/Proto-Father for Father's original form, Mr. Monopoly, Colonel Clean (a.k.a. Sparkleman), Palm Tree, Shota McShadowrape, Ninaxander, the Pimp Suit, Fetus!Envy, Godfather, Scarbro..
Royai for Roy Mustang/Riza Hawkeye, Edwin for Edward/Winry.
Royai kinda counts, but really it's a Bilingual Bonus, with "ai" meaning love.
What Could Have Been: The original, three-hour-long screenplay for Conqueror of Shamballa featured (among many other things) a scene at the end involving Mustang and Winry meeting in front of Hughes's grave and reconciling their differences. This was cut from the final draft and the equivalent scene moved up to the first half of the film, meaning that the last time the audience ever sees Mustang is during the climax, leaving his character arc feeling jarringly unresolved.
