Continuity mistake: During the fight scene at the river, at one point Sean/Guyver gets a large volume of blood spewed onto the shoulder and chest of his suit. About 30 or so seconds later, right after Sean almost accidentally kills Cori, all the blood is suddenly gone from his suit.
Continuity mistake: After Zoanoid-Crane stabs Sean in the final battle, you see quite a bit of blood getting onto Sean's chest/abdomen. A few shots later, when Sean stands back up again, all the blood is gone.
Continuity mistake: When Crane is melting at the end, watch his arm-blades... at one point they go from being perfectly normal, to floppy and "melty", then right back to normal between three cuts.