Continuity mistake: During the stakeout of the apartment building, in the exterior shots of the Clyde Motorcycles shop, Danny is peeking out through a ripped paper opening within the letter "D" in Clyde. However, in the interior shots the black tape letters of the word Clyde differs. The paper is ripped between the two letters "D" and "E" and that space within the "D" is blocked with molding, making what is in the exterior shots quite impossible. (00:15:40)
Continuity mistake: At The End of the episode, a screen shot of Nicki occurs. A day or so earlier, she had been kidnapped and pistol whipped across the face. But this screen shot shows no bruises or swelling or anything, despite being hit so hard she fell over in a chair just a day or so before. (00:40:00)
Continuity mistake: Danny and Jamie are at the pistol range shooting targets. The vantage point from down range shows them both shooting tight shot groups. However, when they are finished shooting, they hold up their targets; their shot groups are not as tight as the down range perspective. (00:34:01)
Fresh Start - S6-E15
Continuity mistake: When Erin is in the ladies' room walking toward the door, she finds Anthony "lurking" in the hall, and Erin's eyeglasses which are hanging from her crew-neck top go from facing her right side, to her left side, then back to her right side, between shots. (00:31:55)
Continuity mistake: As Danny and Jaime are at the range shooting near the middle of the episode, their targets from behind and the grouping of shots they take are really tight together. When they retrieve their targets a minute later, the grouping from the front is completely different and further apart than what was seen from behind the target.
Answer: It's a common cop show plot device. If the police on the show always acted in the most logical way (i.e. not alerting a suspect to their presence) the show wouldn't have the opportunity for an exciting foot chase.