Star Trek: Everything We NOW Know About The Q Continuum
4. The Trouble With Mirrors
The Q Continuum had 'always existed,' according to Q, and by the time Quinn encountered Captain Janeway and the USS Voyager, they had been everywhere and seen everything. This was the story that led to the creation of a new Q child, which sent ripples through time - and led to a potential plot hole in Star Trek's history.
Trelane, posing as the Squire of Gothos, focused his powers using a 'mirror machine,' one that was destroyed by Captain Kirk. Though this did little to rid Trelane of his powers, it did seem to weaken him for however brief a time. However, Wedding Bell Blues confirms that Trelane is Q Junior, the child of Q and the Female Q - so what need was there for a mirror machine at all?
Trelane's true nature had previously been explored in Beta Canon in Peter David's novel Q-Squared. Here, David suggested that the 'mirror machine' was a sort of training device for young Q, like the wheels on a child's first bicycle.
When this is combined with Strange New Worlds' revelation, we can surmise that although Q Junior had previously demonstrated his abilities in Q2, this device was a sort of assignment, or even punishment, for a period of his existence. Wedding Bell Blues seems to take place mid-Q2 in the interval where both he and his father leave Voyager, with the former episode clearly demonstrating Q's supervision over his son.
In truth, the machine has never truly fit into established Q Continuum continuity, though for a species that exists outside of known space-time, that's not all that shocking to discover.