In particular, the ability of the Shield Spell to block Magic Missile is derived from different spells seen later in the film. Indeed, one of the spells seen later even contradicts that notion. So it all depends upon which spell you identify as Magic Missile.
The rules in the Advanced Dungeons & Dragons tradition, of which 5e is the latest descendant, have taken inspiration from film, games, and literature to arrive at a pastiche that diverges significantly from the cinematic original.
Modern gamers interested in genre emulation must either play OD&D, Fantasy Hero, or attempt to house rule something.
I had hoped to be able to offer solutions for 5e, but the design of the game makes that a daunting challenge.
This should be my final word on the topic. I hope you had a Happy Thanksgiving! I look forward to seeing you next time for further explorations into the craft of fantasy.