When Worlds Collide

After discovering that a strange planet is hurtling directly towards Danville, Phineas and Ferb set out to avert a disaster, while Buford looks forward to making contact with its alien race. Meanwhile, Dr. Doofenshirmtz hopes to steal the world's largest ball of twine.

Songs

 * Whalemingo
 * Double Dutch

The "Too Young" Line
None.

Whatcha doin'?
None.

Perry's entrance to his lair
Sleeping in the lawn chair, Perry instantly gets a call and the head rest pulls down, rolling him through some croquet hoops hitting the stake, where he drops down into his lair.

Background Information

 * This episode takes place right after "Gi-Ants".
 * Canadace is only allowed to try and bust the boys once a day.
 * Major Monogram reveals that he wears Seaweed Wrap at Night

Production Information

 * This episode was aired on Disney Channel on Demand on September 7, 2012

Errors

 * Phineas's eyes are pointed in different direction when they built the spring.
 * When the whalemingoes' planet is shot back into space, Buford's hair looks like his 2nd dimension counterpart
 * When the Second time Perry and Doofenshmirtz touch the Double Dutch machine accidentally, Astrophysics.jpgnshmirtz's Panda Designed Slipper disappeared and he began to Double Dutch Barefooted.
 * Ferb's Book entitled Astro Physics spelled in wrong way "Astro Physks" instead of "Astro Physics"

Continuity

 * Fourth episode where the first scene is at Doofenshmirtz Evil Inc. ("Hail Doofania!", "A Real Boy", "The Remains of the Platypus")
 * Third episode to remain at night the entire time ("Candace Gets Busted", "That's the Spirit").
 * When Phineas looks through the telescope, the first thing he sees is the Shooting Star Milkshake Bar. ("Out to Launch")
 * The The Farmer and his wife is seen again.
 * Second time Isabella tries to hold Phineas' hand but instead holding another one by accident. ("That's the Spirit")
 * Third time someone shouts, "My watermelon" ("Phineas and Ferb The Movie: Across the 2nd Dimension", "The Mom Attractor")

Allusions

 * The episode title is a reference to the 1933 science fiction novel, which was made into a movie in 1951.

Cast

 * Vincent Martella as Phineas Flynn
 * Ashley Tisdale as Candace Flynn
 * Thomas Sangster as Ferb Fletcher
 * Caroline Rhea as Linda Flynn-Fletcher
 * Mitchel Musso as Jeremy Johnson
 * Dan Povenmire as Heinz Doofenshmirtz
 * Jeff "Swampy" Marsh as Major Monogram
 * Richard O'Brien as Lawrence Fletcher
 * Dee Bradley Baker as Perry
 * Bobby Gaylor as Buford