The Flash spoilers: Did Harrison Wells kill Barry's mother? Grant Gustin teases time travel when the series returns

The Flash midseason finale introduced fans to the Reverse Flash and teased the possibility of Harrison Wells being the man in the Yellow Suit.

Episode 9 saw the first full appearance of the Reverse Flash, while Barry admits his feelings for Iris and Robbie Amell's character Firestorm's human side is revealed.

Throughout the episode we saw Barry fighting the Yellow streak, and The STAR labs team plotting to trap the man in the yellow suit.

This proves that the Reverse Flash is neither Harrison Wells nor Eddie Thawne as they were present in STAR Labs when the man wearing the yellow mask shows up, but the last few seconds of the episode changed everything.

In the last few minutes Harrison Wells is seen in his secret room, with the yellow suit in his closet, and an evil smirk on his face, confirming that he is the Reverse Flash.

However, there are some loose ends like why the Reverse Flash beat up Dr Wells, why wait this long to make his appearance and why didn't he kill Eddie Thawne?

Moreover, there are several theories whether or not Dr Wells in the one who killed Barry's mother.

Movie pilot speculates that even though Dr Wells is the Reverse Flash, he isn't the one who killed Nora Allen.

According to the report, "The Reverse Flash that was in this episode [and the same one we've been coerced into thinking is Dr. Harrison Wells] has many distinctive features - i.e. a yellow suit, red lightning bolts etc - but one feature is particularly noticeable is the Red Eyes."

The red eyes maybe a feature activated by Dr Wells when he's using his super speed abilities, but the streak that killed Barry's mother had no red eyes, which shows that he isn't the one who killed Nora Allen that night.

Time Travel

In the mid-season finale, Cisco Ramon (Carlos Valdes) pointed out that there wasn't just a ball of yellow lightning surrounding Nora Allen when she was killed, but a red one as well.

In other words, fans already know that a red speedster (presumably Barry) will one day attempt – and fail – to save his mother from her fate, which also teases the introduction of time travel in the show.

A report in Entertainment Weekly said that after the disastrous first battle, Barry will set his sights on testing the limitations of his powers in a bid to match his nemesis, the Reverse Flash.

"We're exploring the vibrating a lot going forward and what the vibrating can do," Grant Gustin said

"And how to slow things down, see things and survey situations with time stopped, essentially."

When asked if the show will deal with time travel, Gustin teased "Maybe", with a high pitch voice of someone trying to keep a secret.

Episode 10 of the The Flash is titled Revenge of the Rogues, which will air Tuesday, 20 January, 2015.

Watch the promo here