OK, you just know Doctor Who didn’t have the budget to go where this episode suggested they were going, so let’s not even pretend for a moment that Mel and the Doctor are going to Disneyland, let along Disneyland in 1959.
Besides, there are bigger problems. An alien queen and her egg are fleeing the genocidal Bannermen. And yes, her name is Delta. She looks like a normal human, but all of her people look like those plastic army men, and you wouldn’t find them in anything Disney in 1959. You have to wait for 1995 for that.
Regardless, Queen Delta goes to hide on a space-faring tour bus full of shapeshifting alien tourists, this time looking human. Now, by this point, you should probably wonder where the Doctor and Mel are, or at least the Doctor if you still aren’t sure what Mel actually brings to the table.
Seriously, I’m usually pretty forgiving of obnoxious companions, but I have no idea why Mel is even here. She seems to mostly exist to talk the Doctor into doing something. Here, for example, when the TARDIS sets down on an alien world and the pair win a prize for being the ten billionth customers, a free trip to Disneyland in 1959, Mel talks the Doctor into accepting. She takes the bus while he follows in the TARDIS.
And then the bus hits a satellite and has to make an emergency landing in South Wales. There is a fun fair there with stuff to do, so it isn’t a total wash, but it sure as hell isn’t Disneyland.
Mel ends up sharing a room with the Queen while the Doctor, the bus driver, and the fair’s mechanic work to repair the bus. The mechanic loves rock’n’roll, alien queens, and ignoring the girl he’s known his whole life who obviously has a thing for him. As such, when Billy sings rock’n’roll ballads to the crowd that night, Mel has to comfort Delta (who has a space gun) while the Doctor comforts the local girl.
Two problems: Mel freaks out when Delta’s egg hatches and the Doctor and the girl are cornered by a space bounty hunter who no only likes money, but he enjoys the killing.
Because, you know, the Bannermen haven’t given up yet.