When Leemo and Cheelai give water to Broly, he is surprised by its appearance and taste, implying that he had never seen water in his life. However, Broly is seen showering in a short scene a few minutes before.
It's implied here that Frieza was the first one to use Scouters, as he offers them to the Saiyan army as part of their service to he and his father's organizations. But flashbacks in the original Dragon Ball Z anime clearly show that it was the Tuffles (the other race living on Planet Vegeta before the Saiyans wiped them out) who first used them, as a means of identifying their invading foes.
When Cheelai summons Shenron during the climax, the dragon grants a single wish before departing; however by this point in the series Shenron had been upgraded to be able to grant three wishes at a time. This is portrayed correctly in previous films such as Resurrection F, and the next movie Super Hero.