This is the first episode where Ray's deceased wife is mentioned.
When Lisa redecorates the mailbox, it's the kind that's on the end of your driveway, but in many episodes, it's very easy to see that they have the kind that's next to their front door.
We find out that the twins' birthday is November 28th, 1979.
When we hear Lisa and Ray arguing at the mall with the security people at one point the Closed Cationing reads "I have never seen this woman in my life," but we never hear Ray say that.
When the Twins are watching a Friday the 13th movie, Tamara says: "Dad, this is Friday the 13th," and Tia says: "Part 14." that was Part 7, and there's no part 14.
(Ray and Lisa show up at the bus station)
Tamera: What are they doing here?
Tia: Oh, I left my mom a note. I didn't want her to worry!
Ray: (To Lisa) No offense lady, but do they call security everywhere you go?
Neighbor: (Off screen) Hey Lisa, Your garbage in the street!
Lisa: Yeah, well and I saw your garbage sneaking through your bedroom window last night!
Tamera: I'll bet you hate algebra and history too. Right?
Tia: No, I like them.
Tamera: That's really weird!
(In Tia's room)
Tia: Wait. Leave the cookies.
Lisa: I'll leave the cookies. I'm taking the pie.
Lisa: By the way, I hit your mailbox.
Ray: But you don't have a car.
Lisa: I was power-walking. I hit it with my purse.
Lisa: Pepe Le Pu owes my daughter an apology.
Sales Clerk: Back back back!
Lisa: Back back back yourself you duck.
Ray: There's no need for name calling.
Lisa: Yo Pinhead!
Tia: Oh my gosh, mom, that girl has my face!
Tia & Tamera: Dad...Mom...that girl has my face!
(Lisa and Ray stare at them both i awe)
Tamera: When was your birthday?
Tia & Tamera: November 28th, 1979!
Tamera: No way! You really are my sister!
Tamera: The weird thing is that when we were seven, we both had a Guinea pig named MC Hamster.
Tia: But then mine died.
Tamera: So did mine!
Tamera: So thats your mom huh?
Tamera: She doesn't seen anything like you.
Tia: I was adopted.
Tamera: Me too.
Tia: When's your birthday?
Tia and Tamera: November 28!
The clerk at the store in this episode, Claude, returns for the finale in a situation almost exactly like this one.
Sister, Sister's pilot aired on the same night as the second episode, so viewers got a whole hour of the show.
George Lemore spent a season on Hangin With Mr. Cooper, a show that aired along with Sister, Sister for two seasons.
MC Hammer: The girls both named their hamsters MC Hamster, paying homage to the popular rapper MC Hammer.
Friday the 13th: A popular horror film series.
Twin Cities: Another name for the Minneapolis/St. Paul area. Also amusing, since the girls discover they are twins, while in the "Twin Cities."