Fans of the Twilight Zone television series know that there are some trademarks to the show from the eerie music that kick off each episode to the black and white motif to Rod Serling himself. Imagineers tried very hard to continue that trend in the Twilight Zone Tower of Terror attraction because the attraction was meant to be a life size television episode. Just like a television episode, there needs to be an introduction and Rod's introduction should sound oddly familiar to those who have seen the series.
In the attraction, you enter the library where the lights cut out and a television turns on to reveal Rod Serling narrating the introduction to the episode you are about to live through. It starts out like any normal episode with Rod saying the following...
"This, as you may recognize, is a maintenance service elevator still in operation, waiting for you."
Since Rod Serling has been dead since 1975 and the Tower of Terror opened in 1994, you may be wondering how they have video of Rod narrating the introduction since the plot of the Tower of Terror was never a Twilight Zone episode. The answer is he only said part of what you hear. The video we see of Rod is from the Twilight Zone episode, "It's a Good Life". In the episode, Rod says, "This, as you may recognize, is a map of the United States." Imagineers edited out the background and cut Rod off halfway and replaced the rest of what he says with a Rod Serling sound-alike named Mark Silverman. During production of the attraction, hundreds of people auditioned for the part of Rod Serling's voice but Mark was chosen for the role by Rod Serling's widow who made the final selection after listening to him on audio tape.
Check out the introduction from the Twilight Zone episode 'It's a Good Life" where you can see the exact video sequence that was used in the attraction and compare it to the previous video and you should see the correlation between the two videos.