When Joe gets off the elevator pretending to talk to Wally's voicemail, you can see that the phone is lit up. Cell phones have a sensor that turn the screen black when brought up to the ear.
When H.R. suggests to reopen Star Labs as a museum and to be the new face of Star Labs, Caitlin and Cisco promptly reject his idea as on Earth-1, Harrison Wells (aka Eobard Thawne) is connected with the murder of Barry's mother and H.R. would be immediately arrested if he were to show his face outside of the Lab. However, in Monster (2016) H.R. hands out coffee and breakfast to everyone which he had to have bought somewhere outside of the facility, yet no one seemed to be worried about that then or thought to tell him about the danger of being falsely recognized as a murderer.