This is how Our Heroes came the Gremlins world and how they take Phineas and Ferb back home in Weekenders Adventures of LEGO Dimensions.
[Our Heroes has came out of the Portal]
Tino: Now where are we, Sunset?
Sunset Shimmer: I don't know.
They saw Gizmo
Gizmo: Gizmo like you.
Tino: Um... Thanks? I guess.
?????: Gizmo, where are you?
It was Phineas and Ferb
Tino: Phineas? Ferb?
Phineas: Tino? I never knew you're here too.
Tino: I thought so too.
Phineas: And I see you met Gizmo, right? Yeah, me and Ferb met him before you arrived.
Tino: I see, so what happened here?
Phineas: I think there's trouble in Gizmo's World.
Tino: So you need our help for Gizmo?
Phineas: Yeah, that's right.
Tino: Alright, you got it!
Phineas: Thanks, come on.
They went off and they saw Stripe coming up for a Plan
Stripe: What will Gizmo
Our Heroes look shock for what Stripe said. He is planning to take over the World
Robotboy: Robotboy stop grenlin.
Tommy: I don't think you could, there's too many of his minions.
Robotgirl: Gremlins hates bright lights!
Sunset Shimmer: I'll get a camera.
Sunset takes the camera to all the Gremlins
Minutes later, Phineas sets the explosive set on the boiler in the theatre , then the gang got out just in time before the theatre explodes and kills the gremlins except Stripe
Phineas: We need to do something for him.
They enter the shop as Homer
Stripe: Homer, caca.
Homer: Camera? Yes!
They take camera at him and they defeated him
Tino: I think we did it.
They take Phineas and Ferb home and our Heroes went to another dimension