These are inventions of Professor E. Gadd that have been created over the course of SMG4's videos.
Bootleg Dimension Portal
The Bootleg Dimension Portal was a failed attempt at creating a magic painting. Gadd warns Mario not to ever enter the painting, but Mario enters the painting anyways, and discovers the Bootleg Dimension and meets Grand Dad. After Mario defeats Grand Dad, he destroys it with a bootleg Bob-omb.
Main article: E. Gadd's Dream invention
E. Gaddifyer 2000
Main article: The E. Gaddifyer 2000
Main article: F.L.U.D.D
Ink Boi 3000
Main article: Ink Boi 3000
A Jetpack is a vehicle E. Gadd useses sometimes in videos.
Launch Stars are major objects in The Mario Galaxy series. One appears in Stupid Mario Galaxy. This particular one was made by Professor E. Gadd.
Main article: Lovebot
Main article: M4R10
The Orb is a object in Overwatch. Mario found one and activated it, causing him and Luigi to temporarily "pass into the Iris." They later returned to reality.
The Poltergust 3000 is a vacuum invented by Professor E. Gadd to catch ghosts. It makes cameos in thought out videos.
Unnamed robots that Professor E. Gadd sold in SMG4: War On Smash Bros Ultimate. It is unknown what their functions are.
The Star Rod is a item from the Kirby series. Luigi cast a spell to see what would happen. However, it caused a bolt of lightning to fire out of the wand and creates a giant hole in the background.
Main article: Shroomy
The Smart-Boi 2000
The Smart-Boi 2000 is a invention that E. Gadd useses to make Mario and Bob smart and later dumb again.
Time Machine (The Weegee Uprising)
This time machine was created by E. Gadd and his descendants to go back in time and stop the Weegee Doll Invasion.
Time Machine Remote