The "Glee" tribute episode for Cory Monteith airs this week and little details about the show have been revealed to get viewers and fans prepared for the episode. Hint: grab some tissues because it seems like it's going to be a tear-jerker.

It was revealed that the episode was going to be a kind of celebration for Monteith and his "Glee" character Finn Hudson. To make the event special for fans many of the original cast members who are no longer a part of the show was asked to come back like Amber Riley (Mercedes), Harry Shum Jr. (Mike Chang), Mark Sailing (Puck) and Jaayma Mays (Emma).

Some other characters making an appearance include Dot-Marie Jones (Coach Bieste), Kurt's father Mike O'Malley (Burt Hummel) and Finn's mother Romy Rosemont (Carole Hudson-Hummel).

Fans were a little confused when it was reported that Dianna Agron, who played Quinn, was not asked to join the others for the tribute episode, especially because she had a big part in Finn's life. According to Radar Online, the 27-year-old actress wasn't asked to come back because no one from the cast likes her.

"It's shocking, because even though she's not contracted for this season, many other actors returned to pay tribute to Cory... even ones with less of a story connection to Finn that Dianna had," the source said. "Remember, she played his GIRLFRIEND on the series, and was a major part of his storyline."

Reportedly actress Lea Michele (who plays Rachel Berry) and co-creator Ryan Murphy "intensely dislike Dianna and have both worked to marginalize her as much as possible."

Agron's character was a cheerleader who joined the school's glee club to keep an eye on Finn, her boyfriend, and eventually ended up becoming a spy for cheerleading coach Sue Slyester, played by Jane Lynch. Quinn was kicked off the Cheerios after discovering she was pregnant, with what was believed to be Finn's child.

She gave birth to a baby girl, Beth, but gave her up for adoption.

"They never saw her as a team player," the source said. "They simply did not want her sharing the glory for this very special episode."

Do you think Dianna Agron should have been invited back for the tribute episode?