A few things that don't add up...

Question

Why are we using "Fantaisie" and not "fantasme or fantastique" - as it my research shows "fantaisie" is to do with the music?
Next is why is it "Magie" and not "magique"? As my research shows that magie is to do with magic tricks whereas "magique" is to do with something amazing (i.e the film)
Next why is "S'assurer que" followed by the subjunctive "soit"? I've looked up this phrase and it says it's always followed by the indicative?

Accepted Answer

Bonjour James,
Maarten is correct as to the use of "magie" and "fantaisie".
Le Subjonctif is used after "s'assurer" because of "afin que / pour que" (and not because of "s'assurer que"). You can take away "to make sure that" and replace it with "so that/in order that", which is translated with "afin que / pour que" - and both are followed by Le Subjonctif.
I hope this is helpful.
Bonne journée !

Answer

James, the first definition of both nouns, magie and fantaisie in wordreference confirm the choices are appropriate to represent the English sense and usage of ‘’the magic’ and ‘the fantasy’. They are certainly in use in spoken French in this manner.

The English text uses magic and fantasy as nouns, and it would be usual translation to do the same in French as long as it is ‘colloquial’ as it is here.

Magique and fantastique are predominantly used as adjectives or as part of compound nouns :

https://www.wordreference.com/fren/magie

https://www.wordreference.com/fren/fantaisie

I will leave the team to comment fully on ‘ s’assurer que’. Although Laura Lawless states it does not need the subjunctive, some other sites add the caveat that it can be used if the speaker is harbouring doubt, so context would be important. In the context used here, I think there could be doubt about the outcome either being the true purpose, or guaranteed. Will be interesting to see if it’s a mistake, or accords with ‘conveying doubt’ intention, or something else.

Answer

I think that s'assurer is similar to espérer: both use the indicative by default but may be used with the subjunctive if there is significant doubt involved, which the speaker wants to emphasize.