* CastIncest: Early in the show's run, onscreen mother and son Joely Richardson (Julia) and John Hensley (Matt) were dating in real life (regardless of their 12-year age difference).
* DawsonCasting: Really obvious on Matt. It gets a little creepy as the actor playing Matt was dating the actress playing his mom (like Matt didn't have enough issues).
** Julian [=McMahon=] (who is from Australia) and Joely Richardson (from England) as Americans. In general, Richardson's American accent is much more accurate than [=McMahon=]'s (except when she says the word "family"). [[spoiler: Also, Rhona Mitra who plays Kit [=McGraw=] is revealed to be American, although Mitra is English.]]
** Averted and then played straight with Kit [=McGraw=]. Creator/RhonaMitra used her real British accent in playing the character, but in her last appearance, the character was revealed to be faking it, and used an American accent.
** Also Montrealer Jessalyn Gilsig.
* FakeBrit: Inverted with Jude Watson and [[spoiler: Kit [=McGraw=]]]. They both play as an American character who are faking their British accent for one reason or another, but both Phillip Rhys and [[spoiler:Rhona Mitra]] were born in London, so the accent they're "faking" in the show is actually their authentic accent in real life.
* FakeNationality: American Maggie Stiff portrays Israeli bombing victim Rachel Ben Natan.
* TechnologyMarchesOn: In a third-season episode Troy and [=McNamara=] attempt a full face transplant, which they admit while theoretically possible, has never been done successfully. Sure enough, in the episode the procedure ultimately fails as the recipient's body rejects the transplant. The world's first successful full face transplant was accomplished in 2010 in Spain.
* TheOtherDarrin: Teddy Rowe is played by Katee Sackhoff, then Creator/RoseMcGowan.
* RealLifeRelative: Julia's mother is actually played by the actress's real-life mother Vanessa Redgrave.