Ralph received high praise for being the only team member to correctly suspect Thawne’s master plan, with reviewers enjoying his evolution from comic relief to a competent detective.

Many reviewers, including those from Den of Geek , felt the hour was the most crowded of the season, rushing to resolve 20 episodes of plot threads before the finale.

Despite the "overprotective parents" trope, critics appreciated Nora’s eventual recognition as a hero in her own right, particularly through her use of a psychic link with Cicada.

The episode concludes on a jarring cliffhanger where Ralph tries to stop Barry from destroying Cicada's dagger. Some fans on Reddit and Den of Geek found the editing of this final moment too sudden, though it effectively set the stage for the finale. Ratings Summary The Flash Season 5 Episode 21 Review - Den of Geek

" The Girl With The Red Lightning " (The Flash Season 5, Episode 21) is widely regarded by critics as a "table-setting" penultimate episode that balances high-stakes action with significant character growth, though some found it overstuffed .

Critics at Rotten Tomatoes noted that while the opening and closing scenes were gripping, the middle sections—particularly the recurring parenting drama between Barry, Iris, and Nora—felt repetitive.

IGN argued that the episode proved Cicada II lacked the weight of past Flash villains, making the struggle against her feel less compelling than the looming threat of Reverse-Flash. Plot & Character Highlights