I watched Voyage of the Rock Aliens the other day which didn't stand the test of 1984, let alone the test of time. It's a great example of practical effects that can stand up to modern scrutiny... and those that can't. The flying V spaceship looks better than CGI in B-movies today, and the talking fire-hydrant robot had more character than BB-8 in the most recent Star Wars films.

But the sheet of plexiglass used as a "force field" was comically terrible, even for 1984