Yes, it is rather like Shiva, Brahma, and Vishnu, except I'm not sure they can all appear at once. To the best of my understanding, it's the Father and the Son of the trinity that matter most, and the Holy Ghost was just thrown in there because it's mentioned somewhere in the Bible. The important thing is that Jesus talks to God, so they can't be the same, right? But they're both God because if not then that denies the divinity of Jesus, thus making the sacrifice pointless, etc. etc.
It's not quite like Voltron, because (at least according to Wikipedia) Voltron is just multiple robots combining to make a bigger robot, whereas each part of the Trinity is supposed to be fully God. At the same time. Go figure.
The trinity isn't mentioned in the Bible, really. It's just a way the priests handwave the contradiction of Jesus both being God and referring to God as his father, and I think John is the book where the Holy Ghost is mentioned, so for some reason they threw that in there too. It's a way of being polytheistic while claiming to be monotheistic.
It's utter bullshit, and the fact is that the different sects can't even agree on what it means, which makes it useless bullshit, unless you want to point this out to your friend.