May 23, 2017 is given as the date of Iris' murder by Savitar. This is the scheduled airdate of the season three finale.
When Barry & Cisco travel to the future, one of the news headlines mentions that "Music Meister gets a six-figure book deal". This is a teaser for the musical crossover between The Flash & Supergirl.
Barry waking up in bed next to Iris after having a nightmare about Savitar is similar to the season 2 episode Potential Energy, where he wakes up in bed next to Patty after having a similar nightmare about Zoom.
H.R. gives Barry a turtle named McSnurtle as a housewarming present. Iris previously owned a stuffed toy turtle by the same name. McSnurtle is the secret identity of the Terrific Whatzit, DC comic's first funny animal comic book character. The Terrific Whatzit possessed superpowers similar to those of Jay Garrick, the Golden Age Flash, and wore a similar costume.
McSnurtle the Turtle is also a reference to a story in the children's comic DC Super Friends. In that story, Barry adopts a pet turtle to become his representative in the Legion of Super Pets, ignoring the fact that the completely normal turtle has no powers.