If you look closely, it's revealed that Carlos is left-handed when he's signing the Valentine's Day card.
The episode title is from John Paul Young's classic hit, 'Love is in the Air' (1977).
The Scavo twins say they are 6-years-old, and Parker says he is 5. In real-life, the actor who played Parker (Zane Huett), is six months older than the actors who played the twins (Brent & Shane Kinsman). While filming this episode, the twins were actually 7-years-old, and Huett was almost 8, despite the latter playing a 5-year-old.
Mary Alice says in her narration: "...and jewelry made at the Scout jamboree". In Scouting, a jamboree is a large gathering of Scouts and/or Girl Guides, who rally at a national or international level. The word "jamboree" was coined following the first Boy Scout jamboree in 1920, when new attendees were warmly welcomed with the word "jambo", which means "Hello" in Swahili.