The Flash's extensive cameos notably didn't include Grant Gustin's Arrowverse iteration of Barry Allen - which makes one cameo controversy way worse.
One cameo in The Flash makes the decision to not include an appearance from Grant Gustin's Barry Allen even worse. DC's newest movie has a somewhat complicated reputation among audiences, to say the least. The Flash has simultaneously been lauded by many critics, and yet also has received a considerable amount of criticism, which is largely based around the way it adapted the Flashpoint comic, the somewhat jarring VFX used throughout the plot, and the questionable cameo decisions made in the final act of the movie.
The Flash includes a wide range of cameos within its
multiversal plot, so the decision to not include Grant Gustin's Flash drew
confusion from audiences acquainted with the Arrowverse iteration of the
hero. This was partially because leaving one of the most recognizable Flash
actors for the past decade out felt like a snub to many, but also because
instead of Gustin's Barry, The Flash cameos included a "generic Golden Age
Flash", which felt odd when every other cameo features actors who were
previously associated with a superhero role. The decision to use a generic
Flash also accidentally served to make one movie controversy all the more
potent.
The Flash's "Generic" Jay Garrick Cameo Makes Its Controversial
Cameos Worse
The Flash featuring cameos from Christopher Reeves and George
Reeves using deepfake technology and CGI is all the more controversial when
the decision to include a "generic" Jay Garrick makes it clear this avenue
could have also been used instead of digitally recreating deceased actors.
This is especially true given the respective circumstances of both
individuals, as Christopher Reeves stated in interview that he wouldn't wish
to reprise his role as Superman unless he personally believed in a project,
and George Reeves' career as Superman has been speculated to have played a
role in his death by suicide due to the difficulty he faced getting other
roles after playing the superhero.
While the Superman cameos were likely picked for their
historical significance, picking cameo recreations of actors who evidence
suggests may not have wanted to appear in the movie were they able to choose
so was always set to alienate the very fans who loved both Superman roles.
Instead, The Flash could have used Grant Gustin's Barry Allen as their big
cameo appearance, as this would've avoided the controversy while also
appealing to the not inconsiderable Arrowverse fanbase.
Why The Flash Didn't Include A Cameo From Another Franchise's Flash
Notably, the explanation for Gran Gustin not appearing in The
Flash was later revealed to be because the studio "had to pick" from a
selection of possible cameos, and Gustin's Barry Allen didn't make the cut.
Indeed, despite Spider-Man: Across The Spider-Verse showing how possible and
potent multimedia multiverse cameos can be, The Flash doesn't include cameos
from any other franchise's version of the Scarlet Speedster, including the
selection of animated iterations of the Flash also available.
This decision does make sense, as it allows the movie to more
intently focus on the two versions of Barry Allen who star in The Flash.
However, it also limits the ability of the plot to show how important the
superhero truly is, as the big multiverse reveal scenes instead show a range
of versions of Superman and Batman, with the use of one generic alternate
version of Flash almost suggesting the movie's titular hero isn't as
important. As such, The Flash would've benefited from including Grant
Gustin's Barry Allen into the mix, if only to show the real world history
and potency of this particular superhero role.