controller.rb

def track_event_on_mixpanel
  Resque.enqueue MixpanelTrackEventJob, "Event", properties, env
end

mixpanel_track_event_job.rb

class MixpanelTrackEventJob
  @queue = :slow

  def self.mixpanel env
    Mixpanel::Tracker.new MIXPANEL_TOKEN, { :env => env }
  end

  def self.perform name, properties, env
    mixpanel(env).track name, properties
  end
end

resque.rb

rails_root = Rails.root                                                                                                                                   
rails_env = Rails.env      

resque_config = YAML.load_file(rails_root.to_s + '/config/resque.yml')
Resque.redis = resque_config[rails_env]

resque.yml

development: localhost:6379
production: localhost:6379