On the tape of Isabel using her powers, she says "yes Mom, I'm fine", where as when it actually happened she said "yes Mother, I'm fine".
TRIVIA: Featured music in this episode -
-Destiny by Zero 7
-Floating by Smooth
-Red by Elbow
-Dying Slow by Speed Not Steel
-Nullarbor Song by Kasey Chambers
-The One by Oh Susanna
The tape that Mr and Mrs Evans make to spy on Isabel, is dated 11/05/02.
When Max is talking to his dad in the Kitchen about giving up his son, the calendar on the wall behind them is 'April 2002'.
This is one of only two episodes that have the word "Alien" in the title.
TRIVIA: Philip and Diane finally discover the truth about Max and Isabel's true identity.
TRIVIA: This episode marks the final appearance of Emilie de Ravin, as her character, Tess Harding, dies in this episode.
Jesse: You all right?
Isabel: Are you kidding? Max is with Tess. My parents think I'm some kind of freak.
Jesse: Look, it's going to be okay. Max can take care of himself and your parents will love you regardless.
Isabel: I don't know, Jesse. Do you?
Isabel: I can't believe that you spied on me.
Diane: I'm sorry, honey, but we didn't know what else to do.
Philip: Can you please just tell us what this means? Who are you?
Max: We're your kids.
Philip: Are you?
Liz (comforting Max): I'm here, I'll always be here.
Max (with tears in his eyes, about his son, Zan) He's human. He deserves to live a normal human life. look, all I've wanted for the past year, more than anything else in my life, was to find him. And now that I finally have, I- (he pauses) I think that I'm going to have to give him up.
Kyle: We took you into our home, Tess. We protected you, and how did you repay us? You brainwashed me into carrying Alex's dead body.
Tess: I never meant to hurt-
Kyle: Well, too late!
Tess: You've never even heard my side of the story.
Kyle: You have a side? The murderer has a side.
Tess: I was raised by a killer, Kyle. A sick and twisted man...
Kyle: Don't try to play the victim here, Tess. You know, of all the aliens I've met, you're the only one who has no soul.
Tess: Max loves you. Every time we were together, every time we kissed he was thinking of you. He had these flashes that I saw and they were always of you.
Liz: Why are you telling me this?
Tess: Because I know how much it must have hurt you.
Liz: So you're really going to go do this?
Tess: At least I can do one good thing with my life.
Liz: You just did.
Max (as Tess tries to leave the room): Sit…down!
Tess (points at her injured leg): I guess it would be too much to ask you to heal this?
Max: Making you feel better is not one of my priorities.
Liz (as she raises her hand and sends Tess sprawling across the room): Get up bitch!
Kyle (about Tess): She has the baby? Are you kidding me? My brain's exploding.
Kyle: Why haven't you killed her yet?
Michael: Max wouldn't let me.
Kyle: We're screwed.
Tess: Why didn't you vote against me?
Liz: 'Cause I'm not a killer, Tess.
William Sadler, who plays Jim Valenti directed this episode.
Title: Four Aliens and A Baby
This is a reference to to the 1987 movie Three Men And A Baby.