When Riker was sucked into Armus, Jonathan Frakes was in fact submerged in a pool of Metamucil and printer's ink. During a break in filming while Frakes was lying on the beach, covered in the sludge, LeVar Burton approached him and said "Frakes, I never would have done that!"
For the scene where Riker is pulled into the oil, a stuntman was used as a stand-in for Jonathan Frakes. Where Riker's face emerges from the oil, it was actually a plaster cast of Frakes' face painted black. It was placed on the same grate used to lift Mart McChesney and filmed lifting him out of the liquid.
Picard quotes the dark spirit Demogorgon in Percy Bysshe Shelley's "Prometheus Unbound" when he says, "All spirits are enslaved which serve things evil."
In his online review of Hide and Q (1987), Wil Wheaton commented on how in the first season Michael Dorn as Worf didn't do much more than Denise Crosby did and that Worf was, according to Wheaton, "one-dimensional and so incredibly stupid," but eventually Dorn was able to develop Worf into a much more complex and beloved character, whereas Crosby, out of frustration, just quit the show.
Lynch would be the final Enterprise Chief Engineer depicted or referred to onscreen prior to La Forge taking the position permanently by the start of season two.