When Lana's Sprint phone receives an incoming photo, it's a Motorola ringtone used only by this manufacturer.
While Chloe and Clark were speaking in the granary, it is possible to observe behind Chloe the silhouette of a person. It might be a spy, but the conclusion of the plot is different and does not provide an explanation of such a person.
This episode revolves around a chisel that Lana has that was badly damaged when Lex attempted to stab Clarke. In order for the chisel to bend, Lex would have had to exhort superhuman strength.