"When Aliens Collide" is the the twenty-ninth episode of Darkwing Duck.
Drake has taken Gosalyn, Honker, and Tank out for an evening because he lost a coin toss with Herb Muddlefoot. As they are walking home, an alien spaceship passes over them and crashes in the park. Gosalyn goes to look at it and Drake tells her to get away from it. A door opens up and flattens Drake. An alien appears and comes out of the ship. It has some kind of collar on it that it wants them to get off. Tank finds a device that looks like a cucumber and opens it and sees what looks like several blue jawbreakers inside. The alien starts to chase him to get it and he uses Honker to distract the alien while he switches the blue things for rocks. Just as he finishes, the alien grabs the device and Tank has hidden the blue balls in Honker's backpack. Drake and Gosalyn take the alien home with them at Gosalyn's insistence and she wants to get the collar off of him Launchpad shows up and is wearing a ridiculous outfit and scares the alien. Gosalyn takes it into the kitchen to attempt to get the collar off. The alien opens the device and sees that there are just rocks inside it and Gosalyn shows up with a blowtorch and the alien panics. Launchpad tells Drake the story behind what he was wearing at the time and the alien comes running in and runs into Drake. Gosalyn comes in with a chain saw this time and the alien starts to panic. He starts to expand himself and fill the room. Drake pokes him with a pin and he deflates and punches a hole in the roof. As he gets out of the hole and onto the roof he hears Tank and stretches his eyes over to the Muddlefoot's house to spy on Tank. He sees Tank take the blue balls and put them in a jar. Gosalyn gets up on the roof to check on him and he uses the antenna on the roof to spring himself over into the Muddlefoot's house. He runs into Tank as Tank is carrying Honker's backpack. The alien grabs the backpack and expands himself to threaten Tank but the collar causes him to shrink back and Tank mocks the alien. Gosalyn comes running in and kicks Tank into the wall. The alien runs out with the backpack much to Honker's dismay. The alien uses the Muddlefoot's antenna to spring himself back to Drake's house and slams into Drake. The alien goes to the door and runs into Honker. Honker asks if he can have his backpack back and the alien expands and throws Honker across the yard. Then another spaceship in the form of a giant metal cabbage lands and a robot comes out. It is looking for the alien and calls it Wacko. It crashes into the house and grabs Wacko and takes him out. Darkwing shows up and gets blasted by the robot. Gosalyn then jumps on it and pushes its blinders down and temporarily blinds it. Gosalyn grabs Wacko and tosses him towards the ship. Darkwing tells Gosalyn to go to her room as he and Launchpad face off against the robot. Gosalyn slips out and finds Honker at the ship. She asks where Wacko went and Honker tells her he went on the ship. Just then it starts to take off and Gosalyn grabs honker and they get on board. Meanwhile the robot has a hold of Darkwing and Launchpad and tells them he is with the Space Patrol and Wacko is a dangerous criminal who stole the items that look like blue marbles. They hear the ship taking off and go outside just in time to see Gosalyn on it as it speeds away. Darkwing, Launchpad, and the robot go to Darkwing's hideout and they rig the Thunderquack to go into space and fly off after the ship. Gosalyn and Honker are able to get the collar off of Wacko and he starts to talk. He opens the backpack and finds out the the seismospheres (the blue marbles) are not there. Gosalyn says that Tank probably still has them and they turn around and go back. Tank is looking at the spheres and throws away the smallest one. It lands and blows up the house to Tank's shock and amazement. He passes out. Wacko passes the Thunderquack and Launchpad turns around and they follow them. Wacko's ship runs out of fuel and Launchpad crashes into them and they board the ship. They look for Wacko and ask Gosalyn where he is. She refuses to tell them and then Wacko sneaks aboard the Thunderquack and Darkwing asks why she did that. She refuses to believe that he is a criminal and he then starts to take off and leaves the hole open and all the air starts to rush out and Gosaly is swept up. She grabs a hold of something and holds on. The robot shoots a plunger at the hole and seals the ship once again. Gosalyn refuses to believe that Wacko is a criminal. Honker finds one of the spheres in his pocket and they use it to jump start the engines. Wacko crash lands and goes to Tank's room and threatens Tank into telling him where the spheres are. Tanks points to where they are and Wacko grabs them. Darkwing and the robot show up and Wacko threatens to blow them up unless they leave him alone. He goes outside and starts to board the ship. He tells them that he will destroy the universe and Gosalyn overhears this and gets mad that she was wrong about him. She pokes him in the eyes and he drops the jar and Honker grabs it. Gosalyn tells Darkwing that Wacko is all his and Darkwing puts another collar on him. The robot takes Wacko away and blasts off. Herb Muddlefoot shows up and thanks Drake for taking care of the kids. He slams the door and the house falls in.
- The plot of this episode is similar to that of the film Lilo & Stitch. Both feature a little girl taking in a pet, that's really an alien criminal.
Home video releases
- Darkwing Duck: Volume 1