The Angels are hoping it is not serious and they'll have Kotchman back shortly, manager Mike Scioscia said.
After doubling to left in the seventh inning, Kotchman was hit flush in the helmet on an attempted pickoff throw by catcher Russell Martin at second base.
Kotchman stayed down for several minutes before getting up. He was assisted from the field, replaced by Robb Quinlan.
Anderson didn't have his natural motion making a backhanded catch of a drive to the left-center-field gap by Juan Pierre. He made the play, but didn't bend in his normal manner in doing so.
"Garret felt good the last couple days and felt good this morning," Scioscia said. "When he went for the ball, at first it was tough seeing it. When he picked it up, he got his jump to go and felt that his leg was weak. He didn't have the strength to do what he needed to do.
"Obviously, there's something still wrong, and we're going to do everything we can to get it where it needs to be."
Anderson initially suffered a slight tear of the hip flexor tendon running to first base in Chicago on April 27, and was placed on the disabled list for only the second time in his 13-year career as one of the game's most durable performers.
He returned to the active roster on June 2, and was appearing in his 12th game since the injury, batting .265 during the stretch.
The club's all-time leader in games, hits, total bases and RBIs, Anderson is batting .264 this season with three homers and 15 RBIs in 129 at-bats. He'll turn 35 on June 30, but not where he wants to be -- on the DL.
Anderson was saying he rediscovered his stroke right before the current road trip, feeling the quickness return to his hands. He had seven hits in his previous 18 at-bats (.389) before Saturday's game.
Anderson, upbeat before the series in anticipation of playing in the ballpark he visited as a kid from the San Fernando Valley, left after the game and was unavailable for comment.
Kotchman is batting .333 and also is among the American League leaders in on-base percentage (.411) and slugging percentage (.556).
"Casey was woozy," Scioscia said. "He's probably going to be woozy for a while. He got a little cut up there [on his forehead] as well. I couldn't tell exactly what happened.
"We'll see when he can get back. We want to see where he is in a day or two. Hopefully, he's not out too long. Kotch is playing great baseball -- everything from knocking runs in to driving the ball to the great defense he plays."
Quinlan and Shea Hillenbrand are available to play first base in Kotchman's absence.
A roster move will be made to replace Anderson, but infielder Maicer Izturis (right hamstring) is not ready, Scioscia said. Candidates include Triple-A Salt Lake outfielders Tommy Murphy, Nick Gorneault and Terry Evans, first baseman Kendry Morales and infielders Brandon Wood and Matt Brown.