Tim mentions a gangster film on TV is an "old detective movie." The clip being shown is actually "Angels With Filthy Souls", a movie-within-a-movie which was featured in the original Home Alone (1990).
The realistic style of the Pokémon were based on the artwork by RJ Palmer. The movie's production designer discovered him while he was looking for realistic Pokémon designs on the internet, and he was so impressed by Palmer's artwork that he gave him a job as the concept artist for the movie.
Pete Dionne, a VFX Supervisor at MPC, stated that, in designing the Pokémon for the film, one thing that the Pokémon Company was uncompromising on was 'all Pokemon, no matter what the circumstances, need to remain adorable.'
The day before the film's theatrical release, the entire movie was "leaked" onto YouTube. In reality, clicking this video will play a minute of the film, before cutting to a loop of Pikachu dancing for an hour and forty five minutes.
The voice over for large crowd chants were recorded during the Pokémon World Championships 2018 in Nashville.