Luka: I still remember my first day. An oxygen tank rocketed through the ER. Almost killed me.
Kerry: Well, no one said this was the safest place to work.
The scene Luka is describing is from the Season 6 premiere, "
Leave it to Weaver." Though it was filmed on
Goran Visnjic's first shooting day, it was not actually the character Luka's first day in the ER; later in that episode, when Carol responds to Luka's comment that he doesn't feel trusted, she notes that he has now worked at County two or three times.