Dregg was presumed dead when the Dreadnaught exploded in the black hole in the last episode, The Day the Earth Disappeared. There is no mention of how he exactly survived the catastrophic explosion.
The Technodrome is seen on a small hill. But In "Turtle Trek" it was dragged in a crater.
Dregg claimed to have the Turtles at his mercy with both Krang's and Shredder's mental powers, but he only succeeded in gaining Krang's.
Krang's Android body was last being used by Krang when they escaped in "Shredder Triumphant"; however, it is now back in the Technodrome with no explanation.
When Michelangelo and Donatello are battling Dregg inside Krang's Android body, April says, "What is that?" How did April not recognize Krang's Android body when she had seen it many times before?
Donatello says that Krang's android body can expand, but in Shreddered & Splintered, he knocked out the Molecular Amplification Unit's crystal, so unless Krang had a new one installed, there was no way for the body to expand. But when Krang tuned up his robotic body back in Krangenstein Lives, it had the ability to grow and shrink, but that feature had not been used since.
During the dimension where Leonardo and Donatello landed in has a yellow sky, but during the part where they fight off the ground vines, the sky becomes dark blue.
When Leonardo and Donatello are attacked by the vines in the alternate universe they are stuck in, Leonardo is (in at least two sequences) colored to be Raphael.
The only appearance of Professor Huxley and the Globfather.
When Donatello is making the helmet to tap into the phone lines he has Raphael's colors.
Krang lost his Bubble Walker in A Turtle In Time, but he still has it in this episode.
Shredder and Krang found the necessary equipment to restore Krang's mental power in a random building.
Dregg sets the tansporter to tranport any usable steel causing Krang to lose his BubbleWalker. Yet Shredder did not lose his armor.
"The Power of Three" ends with Dregg absorbing everyone's life energy, including Shredder's. However, in this episode Shredder escapes.
When Dregg transports everybody Shredder is in April's car, but before they were transported, he was on top of April's car fighting Leonardo.
Another mistake about the Viper: Previously (And in real life) the car is a two seater, here it's got back seats.
In the previous episodes April's red Dodge Viper sports car is a roadster, here it's become a coupe.
Ironically, April is watching the Channel Six news.
When Raphael, Michaelangelo, and Carter arrived at the animal warehouse, why was there a gorilla just standing there not in a cage? That most definitely would not be safe.
From this episode onwards, Mung is Dregg's second in command, and Hi-Tech gets blasted into space to orbit the galaxy. (Needless to say, this is Hi-Tech's final appearance as well.)